Here is a quick tutorial for trying out GraphChi collaborative filtering toolbox that I wrote. Currently it supports ALS (alternating least squares), SGD (stochastic gradient descent), biasSGD (biased stochastic gradient descent) , SVD++ , NMF (nonnegative matrix factorization), SVD (restarted lanczos, and one sided lanczos), RBM (restricted Bolzman machines), FM (factorization machines) and timeSVD++, CLiMF (collaborative less is more filtering). I am soon going to implement several more algorithms.
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References
Here are papers which explain the algorithms in more detail: Alternating Least Squares (ALS)
Yunhong Zhou, Dennis Wilkinson, Robert Schreiber and Rong Pan. LargeScale Parallel Collaborative Filtering for the Netflix Prize. Proceedings of the 4th international conference on Algorithmic Aspects in Information and Management. Shanghai, China pp. 337348, 2008.
 Alternating Least Squares (ALS)  parallel coordinate descent (a.k.a. CCD++)
H.F. Yu, C.J. Hsieh, S. Si, I. S. Dhillon, Scalable Coordinate Descent Approaches to Parallel Matrix Factorization for Recommender Systems. IEEE International Conference on Data Mining(ICDM), December 2012. Steffen Rendle, Zeno Gantner, Christoph Freudenthaler, and Lars SchmidtThieme. Fast contextaware recommendations with factorization machines. In Proceedings of the 34th international ACM SIGIR conference on Research and development in Information Retrieval (SIGIR '11). ACM, New York, NY, USA, 635644.
 Stochastic gradient descent (SGD)
Matrix Factorization Techniques for Recommender Systems Yehuda Koren, Robert Bell, Chris Volinsky In IEEE Computer, Vol. 42, No. 8. (07 August 2009), pp. 3037. Takács, G, Pilászy, I., Németh, B. and Tikk, D. (2009). Scalable Collaborative Filtering Approaches for Large Recommender Systems. Journal of Machine Learning Research, 10, 623656.
 Bias stochastic gradient descent (BiasSGD)
Y. Koren. Factorization Meets the Neighborhood: a Multifaceted Collaborative Filtering Model. ACM SIGKDD 2008. Equation (5).
 SVD++
Y. Koren. Factorization Meets the Neighborhood: a Multifaceted Collaborative Filtering Model. ACM SIGKDD 2008.
 WeightedALS
Collaborative Filtering for Implicit Feedback Datasets Hu, Y.; Koren, Y.; Volinsky, C. IEEE International Conference on Data Mining (ICDM 2008), IEEE (2008).
 SparseALS
Xi Chen, Yanjun Qi, Bing Bai, Qihang Lin and Jaime Carbonell. Sparse Latent Semantic Analysis. In SIAM International Conference on Data Mining (SDM), 2011. D. Needell, J. A. Tropp CoSaMP: Iterative signal recovery from incomplete and inaccurate samples Applied and Computational Harmonic Analysis, Vol. 26, No. 3. (17 Apr 2008), pp. 301321.
 NMF
Lee, D..D., and Seung, H.S., (2001), 'Algorithms for Nonnegative Matrix Factorization', Adv. Neural Info. Proc. Syst. 13, 556562.
 SVD (Restarted Lanczos & One sided Lanczos)
V. Hern´andez, J. E. Rom´an and A. Tom´as. STR8: Restarted Lanczos Bidiagonalization for the SVD in SLEPc.
 tensorALS
Tensor Decompositions, Alternating Least Squares and other Tales. P. Comon, X. Luciani and A. L. F. de Almeida. Special issue, Journal of Chemometrics. In memory of R. Harshman. August 16, 2009
 Restricted Bolzman Machines (RBM)
G. Hinton. A Practical Guide to Training Restricted Boltzmann Machines. University of Toronto Tech report UTML TR 2010003.
 timesvd++
Yehuda Koren. 2009. Collaborative filtering with temporal dynamics. In Proceedings of the 15th ACM SIGKDD international conference on Knowledge discovery and data mining (KDD '09). ACM, New York, NY, USA, 447456. DOI=10.1145/1557019.1557072
 libFM
Steffen Rendle (2010): Factorization Machines, in Proceedings of the 10th IEEE International Conference on Data Mining (ICDM 2010), Sydney, Australia.
 PMF
Salakhutdinov and Mnih, Bayesian Probabilistic Matrix Factorization using Markov Chain Monte Carlo. in International Conference on Machine Learning, 2008.
 CLiMF
CLiMF: learning to maximize reciprocal rank with collaborative lessismore filtering. Yue Shi, Martha Larson, Alexandros Karatzoglou, Nuria Oliver, Linas Baltrunas, Alan Hanjalic, Sixth ACM Conference on Recommender Systems, RecSys '12.
Target
The benefit of using GraphChi is that it requires a single multicore machine and can scale up to very large models, since at no point the data is fully read into memory. In other words, GraphChi is very useful for machine with limited RAM since it streams over the dataset. It is also possible to configure how much RAM to use during the run.Here are some performance numbers:
Netflix has around 100M ratings so the matrix has 100M nonzeros. The size of the decomposed
matrix is about 480K users x 10K movies. I used a single multicore machine with 8 threads, where GraphChi memory consumption was limited to 800Mb, using 8 cores. The factorized matrix has a width of D=20. In total it takes around 80 seconds per 6 iterations, which is around 14 seconds per iteration.
Preprocessing the matrix is done once, and take around 35 seconds.
The input to GraphChi ALS/SGD/biasSGD is the sparse matrix A in sparse matrix market format. The output are two matrices U and V s.t. A ~= U*V' and both U and V have
a lower dimension D.
Running and setup instructions
Let's start with an example:1) Download graphchi from Github using the instructions here.
2) Change directory to graphchi
> cd graphchi
3) Install graphchi
> bash install.sh
4a) For ALS/SGD/biasSGD/SVD++/SVD Download Netflix synthetic sample file. The input is in sparse matrix market format.
wget http://www.select.cs.cmu.edu/code/graphlab/datasets/smallnetflix_mm
wget http://www.select.cs.cmu.edu/code/graphlab/datasets/smallnetflix_mme
4b) For WALS Download netflix sample file including time:
wget http://www.select.cs.cmu.edu/code/graphlab/datasets/time_smallnetflix
wget http://www.select.cs.cmu.edu/code/graphlab/datasets/time_smallnetflixe
5) Run baseline methods on Netflix example:
./toolkits/collaborative_filtering/baseline training=smallnetflix_mm validation=smallnetflix_mm minval=1 maxval=5 quiet=1 algorithm=user_mean
5a) Run ALS on the Netflix example:
./toolkits/collaborative_filtering/als training=smallnetflix_mm validation=smallnetflix_mme lambda=0.065 minval=1 maxval=5 max_iter=6 quiet=1
At the first time, the input file will be preprocessed into an efficient binary representation on disk and then 6 ALS iterations will be run.
5b) Run CCD++ on the Netflix example:
./toolkits/collaborative_filtering/als_coord training=smallnetflix_mm validation=smallnetflix_mme lambda=0.065 minval=1 maxval=5 max_iter=6 quiet=1
5c) Run SGD on the Netflix example:
./toolkits/collaborative_filtering/sgd training=smallnetflix_mm validation=smallnetflix_mme sgd_lambda=1e4 sgd_gamma=1e4 minval=1 maxval=5 max_iter=6 quiet=1
5c) Run biasSGD on the Netflix example:
./toolkits/collaborative_filtering/biassgd training=smallnetflix_mm validation=smallnetflix_mme biassgd_lambda=1e4 biassgd_gamma=1e4 minval=1 maxval=5 max_iter=6 quiet=1
5d) Run SVD++ on Netflix example:
./toolkits/collaborative_filtering/svdpp training=smallnetflix_mm validation=smallnetflix_mme biassgd_lambda=1e4 biassgd_gamma=1e4 minval=1 maxval=5 max_iter=6 quiet=1
5e) Run weightedALS on the Netflix time example:
./toolkits/collaborative_filtering/wals training=time_smallnetflix validation=time_smallnetflixe lambda=0.065 minval=1 maxval=5 max_iter=6 quiet=1
5f) Run NMF on the reverse Netflix example:
./toolkits/collaborative_filtering/nmf training=reverse_netflix.mm minval=1 maxval=5 max_iter=20 quiet=1
./toolkits/collaborative_filtering/svd training=smallnetflix_mm nsv=3 nv=10 max_iter=5 quiet=1 tol=1e1
./toolkits/collaborative_filtering/svd_onesided training=smallnetflix_mm nsv=3 nv=10 max_iter=5 quiet=1 tol=1e1
5h) Run tensorALS on Netflix time example
./toolkits/collaborative_filtering/als_tensor training=time_smallnetflix validation=time_smallnetflixe lambda=0.065 minval=1 maxval=5 max_iter=6 K=27 quiet=1
5i) Run RBM on time_smallnetflix data using the command:
./toolkits/collaborative_filtering/rbm training=smallnetflix_mm validation=smallnetflix_mme minval=1 maxval=5 max_iter=6 quiet=1
5j) Run timesvd++ on time_smallnetflix data:
./toolkits/collaborative_filtering/timesvdpp training=time_smallnetflix validation=time_smallnetflixe minval=1 maxval=5 max_iter=6 quiet=1
5k) Run libFM on time_smallnetflix
./toolkits/collaborative_filtering/libfm training=time_smallnetflix validation=time_smallnetflixe minval=1 maxval=5 max_iter=6 quiet=1
5l) Run PMF on smallnetflix_mm data:
./toolkits/collaborative_filtering/pmf training=smallnetflix_mm quiet=1 minval=1 maxval=5 max_iter=10 pmf_burn_in=5
5m) Run BiasSGD2 on smallnetflix_mm data:
./toolkits/collaborative_filtering/biassgd2 training=smallnetflix_mm minval=1 maxval=5 validation=smallnetflix_mme biassgd_gamma=1e2 biassgd_lambda=1e2 max_iter=10 quiet=1 loss=logistic biassgd_step_dec=0.99999
./toolkits/collaborative_filtering/biassgd2 training=smallnetflix_mm minval=1 maxval=5 validation=smallnetflix_mme biassgd_gamma=1e2 biassgd_lambda=1e2 max_iter=10 quiet=1 loss=abs biassgd_step_dec=0.99999
./toolkits/collaborative_filtering/biassgd2 training=smallnetflix_mm minval=1 maxval=5 validation=smallnetflix_mme biassgd_gamma=1e2 biassgd_lambda=1e2 max_iter=10 quiet=1 loss=square biassgd_step_dec=0.99999
./toolkits/collaborative_filtering/climf training=smallnetflix_mm validation=smallnetflix_mme binary_relevance_thresh=4 sgd_gamma=1e6 max_iter=6 quiet=1 sgd_step_dec=0.9999 sgd_lambda=1e6
6) View the output.
For ALS, CCD++, SGD, biasSGD, WALS, SVD++ , RBM, CLiMF and NMF
Two files are created: filename_U.mm and filename_V.mmThe files store the matrices U and V in dense matrix market format.
head smallnetflix_mm_U.mm
%%MatrixMarket matrix array real general
95526 5
0.693370
1.740420
0.947675
1.328987
1.150084
1.399164
1.292951
0.300416
For tensorALS, timeSVD++
Additional output file named filename_T.mm is created. Prediction is computed as the tensor product of U_i * V_j * T_k (namely r_ijk = sum_l( u_il * v_jl * t_kl )).For biasSGD, SVD++, timeSVD++
Additional three files are created: filename_U_bias.mm, filename_V_bias.mm and filename_global_mean.mm. Bias files include the bias for each user (U) and item (V).The global mean file includes the global mean of the rating.
For SVD
For each singular vector a file named filename.U.XX is created where XX is the number of the singular vector. The same with filename.V.XX. Additionally a singular value files is also saved.Algorithms
Here is a table summarizing the properties of the different algorithms in the collaborative filtering library:ALGORITHM  Method type  Comments 
ALS  ALS  
ALS_COORD/CCD++  ALS  Using parallel coordinate descent 
SparseALS  ALS  Sparse feature vectors (useful for classifying users/items together) 
SGD  SGD  
biasSGD  SGD  
biasSGD2  SGD  Supports logistic loss and MAE 
SVD  Lanczos  
One Sided SVD  For skewed matrices (with one dimension larger than the other)  
NMF  For positive matrices.  
RBM  SGD  MCMC method 
SVD++  SGD  
LIBFM  SGD  
PMF  ALS  MCMC method 
timeSVD++  SGD  Supports time 
BPTF (not implemented yet)  MCMC method  
BaseLine  X  X 
WALS  ALS  Supports weights for each recommendation. 
TENSOR ALS  Tensor factorization.  
GENSGD  Supports arbitrary string format. Can be used for classification.  
SPARSE_GENSGD  libsvm format.  
CLiMF  SGD  Minimizes MRR (mean reciprocal rank) 
Note: for tensor algorithms, you need to verify you have both the rating and its time. Typically the exact time is binned into time bins (a few tens up to a few hundreds). Having too fine granularity over the time bins slows down computation and does not improve prediction.
Using matrix market format, you need to specify each rating using 4 fields:
[user] [item] [time bin] [rating]
Common command line options (for all algorithms)
training  the training input file 
validation  the validation input file (optional). Validation is data with known ratings which not used for training. 
test  the test input file (optional). Test input file is used for computing predictions to a predefined list of user/item pairs. 
minval  min allowed rating (optional). It is highly recommended to set this value since it improves prediction accuracy. 
maxval  max allowed rating (optional). It is highly recommended to set this value since it improves prediction accuracy. 
max_iter  number of iterations to run 
quiet  run with less traces. (optional, default = 0). 
halt_on_rmse_increase  (optional, default = 0). Stops execution when validation error goes up. Runs at least the number of iterations specified in the flag. For example halt_on_rmse_increase=10 will run at least 10 iterations, and then stop if validation RMSE increases. 
load_factors_from_file  (optional, default = 0). This options allows for two functionalities. Instead of starting with a random state, you can start from any predefined state for the algorithm. This also allows for running a few iterations, saving the results to disk for fault tolerance, and running later FROM THE SAME EXACT state. 
D  width of the factorized matrix. Default is 20. 
with R)
Baseline method The baseline method is a simple and quick way of checking the accuracy of the predictions.
The baseline method support three operation modes:
algorithm=global_mean // assigns all recommendations to be the global rating mean.
algorithm=user_mean //assigns recommendations based on each user mean value.
algorithm=item_mean //assigns recommendations based on each item mean value.
To summarize, the baseline method assigns one of the three possible means as the recommendation results and computes the prediction error. Any other algorithm should give a better result than the baseline method, and thus it can be used a sanity check for the deployed algorithms.
ALS (Alternating least squares) Pros: Simple to use, not many command line arguments
Cons: intermediate accuracy, higher computational overhead
ALS is a simple yet powerful algorithm. In this model the prediction is computed as:
r_ui = p_u * q_i
Where r_ui is a scalar rating of user u to item i, and p_u is the user feature vector of size D, q_i is the item feature vector of size D and the product is a vector product.
The output of ALS is two matrices: filename_U.mm and filename_V.mm The matrix U holds the user feature vectors in each row. (Each vector has exactly D columns). The matrix V holds the feature vectors for each time (Each vector has again exactly D columns). In linear algebra notation the rating matrix R ~ UV
Below are ALS related command line options:
Basic Confirmation  lambda=XX  Set regularization. Regularization helps to prevent overfitting. 
CCD++ (Alternating least squares, parallel coordinate descent)
Pros: Simple to use, not many command line arguments, faster than ALS
Cons: Slower convergence relative to ALS
In CCD++ the prediction is computed as:
r_ui = p_u * q_i
Where r_ui is a scalar rating of user u to item i, and p_u is the user feature vector of size D, q_i is the item feature vector of size D and the product is a vector product.
The output of CCD++ are two matrices: filename_U.mm and filename_V.mm The matrix U holds the user feature vectors in each row. (Each vector has exactly D columns). The matrix V holds the feature vectors for each time (Each vector has again exactly D columns). In linear algebra notation the rating matrix R ~ UV
Below are CCD++ related command line options:
Basic
Confirmation lambda=XX Set regularization. Regularization helps to prevent overfitting.
Stochastic gradient descent (SGD)
Pros: fast method
Cons: need to tune step size, more iterations are needed relative to ALS.
SGD is a simple gradient descent algorithm. Prediction in SGD is done as in ALS:
r_ui = p_u * q_i
Where r_ui is a scalar rating of user u to item i, and p_u is the user feature vector of size D, q_i is the item feature vector of size D and the product is a vector product.
The output of SGD is two matrices: filename.U and filename.V. The matrix U holds the user feature vectors in each row. (Each vector has exactly D columns). The matrix V holds the feature vectors for each time (Each vector has again exactly D columns). In linear algebra notation the rating matrix R ~ UV
lambda  regularization (optional). Default value 1e3.Cons: Slower convergence relative to ALS
In CCD++ the prediction is computed as:
r_ui = p_u * q_i
Where r_ui is a scalar rating of user u to item i, and p_u is the user feature vector of size D, q_i is the item feature vector of size D and the product is a vector product.
The output of CCD++ are two matrices: filename_U.mm and filename_V.mm The matrix U holds the user feature vectors in each row. (Each vector has exactly D columns). The matrix V holds the feature vectors for each time (Each vector has again exactly D columns). In linear algebra notation the rating matrix R ~ UV
Below are CCD++ related command line options:
Basic Confirmation  lambda=XX  Set regularization. Regularization helps to prevent overfitting. 
gamma  gradient step size (optional).Default value 1e3.
sgd_step_dec  multiplicative step decrement (optional). Default is 0.9.
BiasSGD
Pros: fast method
Cons: need to tune step size
BiasSGD is a simple gradient descent algorithm, where besides of the feature vector we also compute item and user biases (how much their average rating differs from the global average).
Prediction in biasSGD is done as follows:
r_ui = global_mean_rating + b_u + b_i + p_u * q_i
Where global_mean_rating is the global mean rating, b_u is the bias of user u, b_i is the bias of item i and p_u and q_i are feature vectors as in ALS. You can read more about biasSGD in reference [N].
The output of biasSGD consists of two matrices: filename.U and filename.V. The matrix U holds the user feature vectors in each row. (Each vector has exactly D columns). The matrix V holds the feature vectors for each time (Each vector has again exactly D columns). Additionally, the output consists of two vectors: bias for each user, bias for each item. Last, the global mean rating is also given as output.
biasSGD command line arguments:
biassgd_lambda regularization (optional). Default value 1e3.biassgd_gamma gradient step size (optional). Default value 1e3.
biassgd_step_dec  multiplicative gradient step decrement (optional). Default is 0.9.
BiasSGD2
Pros: fast method, supports logistic loss and MAE
Cons: need to tune step size. Need to supply both minval and maxval, the allowed range for recommendations.
BiasSGD2 is a simple gradient descent algorithm, where besides of the feature vector we also compute item and user biases (how much their average rating differs from the global average).
Prediction in biasSGD is done as follows:
r_ui = global_mean_rating + b_u + b_i + p_u * q_ir_ui = 1/ (1 + exp(rui))r_ui = min_rating + rui * rating_range
Where global_mean_rating is the global mean rating, b_u is the bias of user u, b_i is the bias of item i and p_u and q_i are feature vectors as in ALS. You can read more about biasSGD in reference [N].
The output of biasSGD2 consists of two matrices: filename.U and filename.V. The matrix U holds the user feature vectors in each row. (Each vector has exactly D columns). The matrix V holds the feature vectors for each time (Each vector has again exactly D columns). Additionally, the output consists of two vectors: bias for each user, bias for each item. Last, the global mean rating is also given as output.
biasSGD2 command line arguments:
biassgd_lambda regularization (optional). Default value 1e3.biassgd_gamma gradient step size (optional). Default value 1e3.
biassgd_step_dec  multiplicative gradient step decrement (optional). Default is 0.9.
loss=square/abs/logistic
Koren’s SVD++
Pros: more accurate method than SGD once tuned, relatively fast method
Cons: a lot of parameters for tuning, subject to numerical errors when parameters are out of scope.
Koren SVD++ is an algorithm which is slightly more fancy than biasSGD and give somewhat better prediction results.
Prediction in Koren’s SVD++ algorithm is computed as follows:
r_ui = global_mean_rating + b_u + b_i + q_i * ( p_u + w_u )
Where r_ui is the scalar rating for user u to item i, global_mean_rating is the global mean rating, b_u is a scalar bias for user u, b_i is a scalar bias for item i, p_u is a feature vectors of length D for user u, q_i is a feature vector of length D for item i, and w_u is an additional feature vector of length D (the weight) for user u. The product is a vector product.
The output of Koren’s SVD++ is 5 output files:
Global mean ratings  include the scalar global mean rating.
user_bias  includes a vector with bias for each user
movie_bias  includes a vector with bias for each movie
matrix U  includes in each row the feature vector p_u of size D and then the weight vector w_u of size D total width of 2D.
matrix V  includes in each row the item feature vector q_i of width D.
r_ui = global_mean_rating + b_u + b_i + q_i * ( p_u + w_u )
Where r_ui is the scalar rating for user u to item i, global_mean_rating is the global mean rating, b_u is a scalar bias for user u, b_i is a scalar bias for item i, p_u is a feature vectors of length D for user u, q_i is a feature vector of length D for item i, and w_u is an additional feature vector of length D (the weight) for user u. The product is a vector product.
The output of Koren’s SVD++ is 5 output files:
Global mean ratings  include the scalar global mean rating.
user_bias  includes a vector with bias for each user
movie_bias  includes a vector with bias for each movie
matrix U  includes in each row the feature vector p_u of size D and then the weight vector w_u of size D total width of 2D.
matrix V  includes in each row the item feature vector q_i of width D.
SVD++ command line arguments:
svdpp_item_bias_step, svdpp_user_bias_step, svdpp_user_factor_step, svdpp_user_factor2_step  gradient step size (optional). Default value 1e4.svdpp_item_bias_reg, svdpp_user_bias_reg, svdpp_user_factor_reg, svdpp_user_factor2_reg  regularization (optional). Default value 1e4.
svdpp_step_dec  multiplicative gradient step decrement (optional). Default is 0.9.
Weighted Alternating Least Squares (WALS)
Pros: allows weighting of ratings (can be thought of as confidence in rating), almost the same computational cost like in ALS.
Cons: worse modeling error relative to ALS
Weighted ALS is a simple extension for ALS where each user/item pair has an additional weight. In this sense, WALS is a tensor algorithm since besides of the rating it also maintains a weight for each rating. Algorithm is described in references [I, J].
Prediction in WALS is computed as follows:
r_ui = w_ui * p_u * q_i
The scalar value r for user u and item i is computed by multiplying the weight of the rating w_ui by the vector product p_u * q_i. Both p and q are feature vectors of size D.
Note: for weightedALS, the input file has 4 columns:
Cons: worse modeling error relative to ALS
Weighted ALS is a simple extension for ALS where each user/item pair has an additional weight. In this sense, WALS is a tensor algorithm since besides of the rating it also maintains a weight for each rating. Algorithm is described in references [I, J].
Prediction in WALS is computed as follows:
r_ui = w_ui * p_u * q_i
The scalar value r for user u and item i is computed by multiplying the weight of the rating w_ui by the vector product p_u * q_i. Both p and q are feature vectors of size D.
Note: for weightedALS, the input file has 4 columns:
[user] [item] [weight] [rating]. See example file in section 5e).
Alternating least squares with sparse factors
Pros: excellent for spectral clustering
Cons: less accurate linear model because of the sparsification step
This algorithm is based on ALS, but an additional sparsifying step is performed on either the user feature vectors, the item feature vectors or both. This algorithm is useful for spectral clustering: first the rating matrix is factorized into a product of one or two sparse matrices, and then clustering can be computed on the feature matrices to detect similar users or items.
The underlying algorithm which is used for sparsifying is CoSaMP. See reference [K1].
Below are sparseALS related command line options:
Basic configuration  user_sparsity=XX  A number between 0.5 to 1 which defines how sparse is the resulting user feature factor matrix 
movie_sparsity=XX  A number between 0.5 to 1 which defines how sparse is the resulting movie feature factor matrix  
algorithm=XX 
There are three run modes:
SPARSE_USR_FACTOR = 1
SPARSE_ITM_FACTOR = 2
SPARSE_BOTH_FACTORS = 3

Prediction in sparseALS is computing like in ALS.
Example running sparseALS:
Example running sparseALS:
bickson@thrust:~/graphchi$ ./bin/sparse_als.cpp training=smallnetflix_mm user_sparsity=0.8 movie_sparsity=0.8 algorithm=3 quiet=1 max_iter=15
WARNING: sparse_als.cpp(main:202): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[user_sparsity] => [0.8]
[movie_sparsity] => [0.8]
[algorithm] => [3]
[quiet] => [1]
[max_iter] => [15]
0) Training RMSE: 1.11754 Validation RMSE: 3.82345
1) Training RMSE: 3.75712 Validation RMSE: 3.241
2) Training RMSE: 3.22943 Validation RMSE: 2.03961
3) Training RMSE: 2.10314 Validation RMSE: 2.88369
4) Training RMSE: 2.70826 Validation RMSE: 3.00748
5) Training RMSE: 2.70374 Validation RMSE: 3.16669
6) Training RMSE: 3.03717 Validation RMSE: 3.3131
7) Training RMSE: 3.18988 Validation RMSE: 2.83234
8) Training RMSE: 2.82192 Validation RMSE: 2.68066
9) Training RMSE: 2.29236 Validation RMSE: 1.94994
10) Training RMSE: 1.58655 Validation RMSE: 1.08408
11) Training RMSE: 1.0062 Validation RMSE: 1.22961
12) Training RMSE: 1.05143 Validation RMSE: 1.0448
13) Training RMSE: 0.929382 Validation RMSE: 1.00319
14) Training RMSE: 0.920154 Validation RMSE: 0.996426
tensorALS
Note: for tensorALS, the input file has 4 columns:
[user] [item] [time] [rating]. See example file in section 5b).
lambda  regularization
tensorALS
Note: for tensorALS, the input file has 4 columns:
[user] [item] [time] [rating]. See example file in section 5b).
lambda  regularization
Nonnegative matrix factorization (NMF)
Nonnegative matrix factorization (NMF) is based on Lee and Seung [reference H].
Prediction is computed like in ALS:
r_ui = p_u * q_i
Namely the scalar prediction r of user u is composed of the vector product of the user feature vector p_u (of size D), with the item feature vector q_i (of size D). The only difference is that both p_u and q_i have all nonnegative values.
The output of NMF is two matrices: filename.U and filename.V. The matrix U holds the user feature vectors in each row. (Each vector has exactly D columns). The matrix V holds the feature vectors for each time (Each vector has again exactly D columns). In linear algebra notation the rating matrix R ~ UV, U>=0, V>=0.
NMF Has no special command line arguments.SVD
SVD is implemented using the restarted lanczos algorithm.
The input is a sparse matrix market format input file.
The output are 3 files: one file containing the singular values, and two dense matrix market format files containing the matrices U and V.
Note: for larger models, it is advised to use svd_onesided since it significantly saved memory.
Here is an example Matrix Market input file for the matrix A2:
<2350>bickson@bigbro6:~/ygraphlab/graphlabapi/debug/toolkits/parsers$ cat A2
%%MatrixMarket matrix coordinate real general
3 4 12
1 1 0.8147236863931789
1 2 0.9133758561390194
1 3 0.2784982188670484
1 4 0.9648885351992765
2 1 0.9057919370756192
2 2 0.6323592462254095
2 3 0.5468815192049838
2 4 0.1576130816775483
3 1 0.1269868162935061
3 2 0.09754040499940952
3 3 0.9575068354342976
3 4 0.9705927817606157
Here is an for running SVD :
bickson@thrust:~/graphchi$ ./bin/svd training=A2 nsv=4 nv=4 max_iter=4 quiet=1 WARNING: svd.cpp(main:329): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com [training] => [A2] [nsv] => [4] [nv] => [4] [max_iter] => [4] [quiet] => [1] Load matrix set status to tol Number of computed signular values 4 Singular value 0 2.16097 Error estimate: 2.35435e16 Singular value 1 0.97902 Error estimate: 1.06832e15 Singular value 2 0.554159 Error estimate: 1.56173e15 Singular value 3 9.2673e65 Error estimate: 6.51074e16 Lanczos finished 7.68793
Listing the output files:
#> ls lrt
rwrr 1 bickson bickson 2728 20120920 01:57 graphchi_metrics.txt
rwrr 1 bickson bickson 2847 20120920 01:57 graphchi_metrics.html
rwrr 1 bickson bickson 188 20120920 01:57 A2.V.3
rwrr 1 bickson bickson 179 20120920 01:57 A2.V.2
rwrr 1 bickson bickson 179 20120920 01:57 A2.V.1
rwrr 1 bickson bickson 177 20120920 01:57 A2.V.0
rwrr 1 bickson bickson 208 20120920 01:57 A2.U.3
rwrr 1 bickson bickson 195 20120920 01:57 A2.U.2
rwrr 1 bickson bickson 195 20120920 01:57 A2.U.1
rwrr 1 bickson bickson 194 20120920 01:57 A2.U.0
rwrr 1 bickson bickson 271 20120920 01:57 A2.singular_values
Verifying solution accuracy in matlab
>>A2=mmread('A2');
>> full(A2)'
ans =
0.8147 0.9058 0.1270
0.9134 0.6324 0.0975
0.2785 0.5469 0.9575
0.9649 0.1576 0.9706
Now we read graphchi output using:
% read the top 3 singular values:
>> sigma=mmread('A2.singular_values');
>> sigma=sigma(1:3);
Read the top 3 vectors v:
>> v0=mmread('A2.V.0');
>> v1=mmread('A2.V.1');
>> v2=mmread('A2.V.2');
Read the top 3 vectors u:
>> u0=mmread('A2.U.0');
>> u1=mmread('A2.U.1');
>> u2=mmread('A2.U.2');
Compute an approximation to A2:
>> [u0 u1 u2] * diag(sigma) * [v0 v1 v2]'
ans =
0.8147 0.9058 0.1270
0.9134 0.6324 0.0975
0.2785 0.5469 0.9575
0.9649 0.1576 0.9706
As you can see we got an identical result to A2.
where
>> [u0 u1 u2]
ans =
0.5047 0.5481 0.2737
0.4663 0.4726 0.2139
0.4414 0.4878 0.7115
0.5770 0.4882 0.6108
>> [v0 v1 v2]'
ans =
0.7019 0.5018 0.5055
0.2772 0.4613 0.8428
0.6561 0.7317 0.1847
>> diag(sigma)
ans =
2.1610 0 0
0 0.9790 0
0 0 0.5542
SVD Command line arguments
Basic configuration  training  Input file name (in sparse matrix market format) 
nv  Number of inner steps of each iterations. Typically the number should be greater than the number of singular values you look for.  
nsv  Number of singular values requested. Should be typically less than nv  
ortho_repeats  Number of repeats on the orthogonalization step. Default is 1 (no repeats). Increase this number for higher accuracy but slower execution. Maximal allowed values is 3.  
max_iter  Number of allowed restarts. The minimum is 2= no restart.  
save_vectors=0  Disable saving the factorized matrices U and V to file. On default save_vectors=1.  
tol  Convergence threshold. For large matrices set this number set this number higher (for example 1e1, while for small matrices you can set it to 1e16). As smaller the convergence threshold execution is slower. 
Understanding the error measure
Following Slepc, the error measure is computed by a combination of:sqrt( Av_i  sigma(i) u_i _2^2 + A^Tu_i  sigma(i) V_i _2^2 ) / sigma(i)
Namely, the deviation of the approximation sigma(i) u_i from Av_i , and vice versa.
Scalability
Currently the code was tested with up to 3.5 billion nonzeros on a 24 core machine. Each Lanczos iteration takes about 30 seconds.Difference to Mahout
Mahout SVD solver is implemented using the same Lanczos algorithm. However, there are several differences1) In Mahout there are no restarts, so quality of the solution deteriorates very rapidly, after 510 iterations the solution is no longer accurate. Running without restarts can be done using our solution with the max_iter=2 flag.
2) In Mahout there is a single orthonornalization step in each iteration while in our implementation there are two (after computation of u_i and after v_i ).
3) In Mahout there is no error estimation while we provide for each singular value the approximated error.
4) Our solution is typically x100 times faster than Mahout.
Notes about parameter tuning (In case not enough singular vectors have converged):
SVD have a few tunable parameters you need to play with.
1) tol=XX, this is the tolerance. When not enough singular vectors converge to a desired
tolerance you can increase it, for example from 1e4 to 1e2, etc.
2) nv=XX this number should be larger than nsv. Typically you can try 20% more or even larger.
3) nsv=XX this is the number of the desired singular vectors
4) max_iter=XX  this is the number of restarts. When the algorithm does not converge you can increase the number of restarts.
In other words, the ratings have to be binned into a discrete space. For example, for KDD CUP 2011 rating between 0 to 100 can be binned into 10 bins: 010, 1020 etc. rbm_scaling defines the factor to divide the rating for binning (in the example it is 10). rbm_bins defines how many bins are there in total. In this example we have 11 bins: 0,1,..,10.
Basic configuration  rbm_mult_step_dec=XX  Multiplicative step decrement (should be 0.1 to 1, default is 0.9) 
rbm_alpha=XX  Alpha parameter: gradient descent step size  
rbm_beta=XX  Beta parameter: regularization  
rbm_scaling=XX  Optional. Scale the rating by dividing it with the rbm_scaling constant. For example for KDD cup data rating of 0..100 can be scaled to the bins 0,1,2,3,.. 10 by setting the rbm_scaling=10  
rbm_bins=XX  Total number of binary bins used. For example in Netflix data where we have 1,2,3,4,5 the number of bins is 5 
Advanced topic: Understanding RBM output format and predicting values.
In case you like to use GraphChi output file for computing RBM predictions you should compute the following:
You should implement the RBM prediction function which is found here: https://github.com/GraphChi/graphchicpp/blob/master/toolkits/collaborative_filtering/rbm.cpp#L129L154
Assume D is the feature vector length. The default D=20.
Basically, each user node has 3 fields: h, h0 and h1, each of them is a vector of size 20.
Those vectors are appended to get a single vector of default size 60.
The U matrix has row as the number of users (M) x 60.
Each movie node has 3 fields: ni (a double), bi is a vector of size rbm_bins (the default is 6).
and w is a vector of size rbm_bins * D = 120 in default.
In the output file first the bi vector is written (size = 6) and then w, total of 126.
The V matrix has rows as the number of items (N) x 126.
The bias ni is written into a separate file named _bias.mm, which contains a vector of size
N x 1.
Note that the prediction involves bi, h, w but does not involve h0, h1, ni.
Koren timeSVD++ Pros: more accurate than SVD++
Cons: many parameters to tune, prone to numerical errors.
Koren’s timeSVD++ [Korens paper above] takes into account also the temporal aspect of the rating.
Prediction in timeSVD++ algorithm is computed as follows:
r_uik = global_mean_rating + b_u + b_i + ptemp_u * q_i + x_u * z_k + pu_u * pt_i * q_k
The scalar rating r_uik (rating for intersection of user u, item i, and time bin k) equals the above sum. Like in Koren’s SVD++ the rating equals the sum of the global mean rating and biases for user and item. The following are feature vectors. For the user we have ptemp_i , x_u and pu_u. All of length D. For the item we have additional three feature vectors: ptemp_u, x_u and pu_u.
For the time bins we have z_k and q_k, two feature vectors of size D.
Basic configuration  lrate=XX  Learning rate 
beta  Beta parameter (bias regularization)  
gamma  Gamma parameter (feature vector regularization)  
lrate_mult_dec  Multiplicative step decrement (0.1 to 1, default 0.9)  
D=X  Feature vector width. Common values are 20  150. 
Special Note: This is a tensor factorization algorithm. Please don’t forget to prepare a 4 column matrix market format file, with [user] [ item ] [ time ] [ rating ] in each row.
It is advised to delete intermediate files created by als_tensor, since they have a different format.
Factorization Machines (FM)
GraphChi's libFM algorithm implementation contains a subset of the full libFMfunctionality with only three predictions: user, item and time. Users are encouraged to check the original libFM library: http://www.libfm.org/ for enhanced implementation. libFM library by Steffen Rendle has a track record performance in KDD CUP and is highly recommended collaborative filtering package.
Factorization machines is a SGD type algorithm. It has two differences relative to biasSGD:
1) It handles time information by adding feature vectors for each time bin
2) It adds additional feature for the last item rated for each user.
Those differences are supposed to make it more accurate than biasSGD.
Factorization machines is detailed in reference [P]. There are several variants, here the SGD variant is implemented (and not the ALS).
Prediction in LIBFM is computed as follows:
r_ui = global_mean_rating + b_u + b_i + b_t + b_li + 0.5*sum(p_u.^2 + q_i.^2 + w_t.^2 + s_li.^2  (p_u + q_i + w_t + s_li ).^2)
Where global_mean_rating is the global mean rating, b_u is the bias of user u, b_i is the bias of item i , b_t is the bias of time t, b_li is the bias of the last item li, and p_u is the feature vector of user u, and q_i is the feature vector of item i, w_t is the feature vector of time t, s_li is the feature vector of last item li. All feature vectors have size of D as in ALS. .^2 is the element by element power operation (as in matlab).
The output of LIBFM consists of three matrices: filename.Users, filename.Movies and filename.Times. The matrix Users holds the user feature vectors in each row. (Each vector has exactly D columns). The matrix Movies holds the feature vectors for each item (Each vector has again exactly D columns). The matrix Times holds the feature vectors for each time. Additionally, the output consists of four vectors: bias for each user, bias for each item, bias for each time bin and bias for each last item. Last, the global mean rating is also given as output.
Basic configuration  libfm_rate=XX  Gradient descent step size 
libfm_regw=XX  Gradient descent regularization for biases  
libfm_regv=XX  Gradient descent regularization for feature vectors  
libfm_mult_dec=XX  Multiplicative step decrease. Should be between 0.1 to 1. Default is 0.9  
D=X  Feature vector width. Common values are 20  150. 
PMF
Pros: once tuned, better accuracy than ALS, since it involves extra sampling stepCons: sensitive to numerical errors, needs fine tuning, does not work on every dataset, higher computational cost, higher prediction computational cost.
PMF and BPTF are two Markov Chain Monte Carlo (MCMC) sampling methods. They are based on ALS, but on each step a sampling from the probability is perform for obtaining the next state.
Prediction in PMF/BPTF is like in ALS, but instead of computing one vector product of the current feature vector, the whole chain of products is computed and the average is taken.
More formally, the prediction rule of PMF is:
r_ui = [ p_u(1) * q_i(1) + p_u(2) * q_i(2) + .. + p_u(l) * q_i(l) ] / l
Where l is the length of the chain.
Note: typically in MCMC methods, the first XX samples of the chain are thrown away, so p_u and q_i will start from XX and not from 1.
The prediction rule of BPTF includes a feature vector for each time bin, denote w:
r_uik = [ p_u(1) * q_i(1) * w_k(1) + p_u(2) * q_i(2) * w_k(2) + .. + p_u(l) * q_i(l) * w_k(l) ] / l
Where the product is a tensor product, namely \sum_j p_uj * q_ij * w_kj
Basic configuration  pmf_burn_in=XX  Throw away the first XX samples in the chain 
pmf_additional_output=1  Save as output all the samples in the chain (after the burn in period). Each sample is composed of two feature vectors. Each will be saved on its own file. 
Example running PMF
Here we run 10 iterations of PMF, where the first 5 are discarded (pmf_burn_in) and the rest are used for computing the prediction:
bickson@thrust:~/graphchi$ ./toolkits/collaborative_filtering/pmf training=smallnetflix_mm quiet=1 minval=1 maxval=5 max_iter=10 pmf_burn_in=5
WARNING: common.hpp(print_copyright:104): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
1.24716) Iteration: 0 Training RMSE: 1.56917 Validation RMSE: 2.4979 ratings_per_sec: 0
2.5872) Iteration: 1 Training RMSE: 2.44993 Validation RMSE: 2.03815 ratings_per_sec: 1.16359e+06
3.95615) Iteration: 2 Training RMSE: 1.7831 Validation RMSE: 1.26519 ratings_per_sec: 1.55628e+06
5.33609) Iteration: 3 Training RMSE: 1.08493 Validation RMSE: 1.05008 ratings_per_sec: 1.76283e+06
6.73702) Iteration: 4 Training RMSE: 0.939768 Validation RMSE: 0.993025 ratings_per_sec: 1.88536e+06
Finished burnin period. starting to aggregate samples
8.16872) Iteration: 5 Training RMSE: 0.88499 Validation RMSE: 0.978547 ratings_per_sec: 1.95767e+06
9.54684) Iteration: 6 Training RMSE: 0.864345 Validation RMSE: 0.972835 ratings_per_sec: 2.01243e+06
10.9789) Iteration: 7 Training RMSE: 0.837162 Validation RMSE: 0.948436 ratings_per_sec: 2.04756e+06
12.43) Iteration: 8 Training RMSE: 0.823885 Validation RMSE: 0.939388 ratings_per_sec: 2.0749e+06
13.8361) Iteration: 9 Training RMSE: 0.814482 Validation RMSE: 0.93436 ratings_per_sec: 2.10232e+06
As a sanity check, now we run 10 iteration were all 10 are discarded (pmf_burn_in=10):
bickson@thrust:~/graphchi$ ./toolkits/collaborative_filtering/pmf training=smallnetflix_mm quiet=1 minval=1 maxval=5 max_iter=10 pmf_burn_in=10
WARNING: common.hpp(print_copyright:104): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
1.18773) Iteration: 0 Training RMSE: 1.55811 Validation RMSE: 2.4997 ratings_per_sec: 0
2.56929) Iteration: 1 Training RMSE: 2.45047 Validation RMSE: 2.07669 ratings_per_sec: 1.16566e+06
3.94601) Iteration: 2 Training RMSE: 1.75645 Validation RMSE: 1.32239 ratings_per_sec: 1.56984e+06
5.27586) Iteration: 3 Training RMSE: 1.11416 Validation RMSE: 1.04864 ratings_per_sec: 1.78811e+06
6.69646) Iteration: 4 Training RMSE: 0.937365 Validation RMSE: 0.994412 ratings_per_sec: 1.89396e+06
8.05631) Iteration: 5 Training RMSE: 0.886551 Validation RMSE: 0.978154 ratings_per_sec: 1.97636e+06
9.44744) Iteration: 6 Training RMSE: 0.861688 Validation RMSE: 0.972389 ratings_per_sec: 2.03489e+06
10.8185) Iteration: 7 Training RMSE: 0.846078 Validation RMSE: 0.972082 ratings_per_sec: 2.07996e+06
12.2176) Iteration: 8 Training RMSE: 0.836964 Validation RMSE: 0.971611 ratings_per_sec: 2.1115e+06
13.6285) Iteration: 9 Training RMSE: 0.829531 Validation RMSE: 0.96975 ratings_per_sec: 2.13407e+06
As you can see, the sampling step improves validation prediction from 0.969 to 0.934.
GenSGD
It is recommended to read first the GenSGD detailed case studies here:
http://bickson.blogspot.co.il/2012/12/collaborativefiltering3rdgeneration.html
http://bickson.blogspot.co.il/2012/12/collaborativefiltering3rdgeneration.html
Mandatory configuration  training  Input file 
from_pos  Column number of the feature which is used as "users" in the matrix factorization case. Column number starts from zero.  
to_pos  Column number of the feature which is used as "items" in the matrix factorization case. Column number starts from zero.  
val_pos  Column number of the value (the target variable) we would like to predict. For example the rating in the matrix factorization case. Column number starts from zero.  
file_columns  Number of features in the input (training) file. (Note that from_pos, to_pos, val_pos should be smaller than the file_column number)  
Optional configuation  rehash=1  If some or all of the feature fields are strings, you should use rehash=1 to translate them into numeric ids. If all the fields are numbers, use rehash=0. Default is 0. 
D  Latent feature vector width. Default is 20.  
calc_error=1  When used for classification, calc_error treats the target is binary value and counts how many validation/training instances are wrong. See cuttoff.  
cutoff  When used for binary classification cutoff is the threshold value were prediction > cutoff is positive and position <= cutoff is negative. Default is 0.  
user_file  File name of additional user properties (optional). Each line should start with user id and then a list of features.  
item file  File name of additional item properties (optional). Each line should start with item id and then a list of features.  
limit_rating=X  For debugging: limit the number of rows in training file to X.  
SGD tunable parameters  gensgd_rate1  SGD step size for users (from_pos). Default 1e2. 
gensgd_rate2  SGD step size for items (to_pos). Default 1e2.  
gensgd_rate3  SGD step size of rating features in training file. Default 1e2.  
gensgd_rate4  SGD step size of user/item features in additional feature files. Default 1e2.  
gensgd_mult_dec  SGD multiplicative step size decrement  default 0.9.  
gensgd_regw  SGD bias regularization. Default 1e3.  
gensgd_reg0  SGD global mean regularization. Default 1e1.  
gensgd_regv  SGD features regularization. Default 1e3. 
Prediction computation in gensgd:
Prediction is computed as follows.rating = global_mean + sum_f (bias_f) + 1/2*(sum_f (pvec_f)  sum_f (pvec_f.^2))
Where f is an index going over all the factors involved, pvec_f is the feature vector of
factor f, bias_f is the bias of factor f, and .^2 is elementwise square. See equation (5)
in the libFM paper. (Note: that x_i and x_j are all equal 1 in our implementation).
Output of gensgd
The output of gensgd are the following files:1) a matrix of size f x D, where f is the number of feature vectors used and D is the feature vectors width. Generated filename is training_file_name + "_U.mm".
2) a vector of size f x 1, where f is the number of feature vectors which holds the scalar bias for each feature vector. Generated filename is training_file_name + "_bias_U.mm".
3) the global mean. Generated filename is training_file_name + "_global_mean.mm"
4) Mapping file for each feature. For each feature (each column) there is a map between the
feature string name, and the integer id of this feature, in the arrays (1) and (2) above. The mapping files are generated only when using the rehash=1 option. Generated file names are training_file_name + ".map." + feature_id
CLiMF
CLiMF was contributed by Mark Levy(last.fm). The CLiMF algorithm, described in the paper: CLiMF: learning to maximize reciprocal rank with collaborative lessismore filtering. Yue Shi, Martha Larson, Alexandros Karatzoglou, Nuria Oliver, Linas Baltrunas, Alan Hanjalic, Sixth ACM Conference on Recommender Systems, RecSys '12.CLiMF is a ranking method which optimizes MRR (mean reciprocal rank) which is an information retrieval measure for topK recommenders. CLiMF is a variant of latent factor CF which optimises a significantly different objective function to most methods: instead of trying to predict ratings CLiMF aims to maximise MRR of relevant items. The MRR is the reciprocal rank of the first relevant item found when unseen items are sorted by score i.e. the MRR is 1.0 if the item with the highest score is a relevant prediction, 0.5 if the first item is not relevant but the second is, and so on. By optimising MRR rather than RMSE or similar measures CLiMF naturally promotes diversity as well as accuracy in the recommendations generated. CLiMF uses stochastic gradient ascent to maximise a smoothed lower bound for the actual MRR. It assumes binary relevance, as in friendship or follow relationships, but the graphchi implementation lets you specify a relevance threshold for ratings so you can run the algorithm on standard CF datasets and have the ratings automatically interpreted as binary preferences.
CLiMFrelated commandline options:
binary_relevance_thresh=xx Consider the item liked/relevant if rating is at least this value [default: 0]
halt_on_mrr_decrease Halt if the training set objective (smoothed MRR) decreases [default: false]
num_ratings Consider this many top predicted items when computing actual MRR on validation set [default:10000]
Here is an example on running CLiMF on Netflix data:
./toolkits/collaborative_filtering/climf training=smallnetflix_mm validation=smallnetflix_mme binary_relevance_thresh=4 sgd_gamma=1e6 max_iter=6 quiet=1 sgd_step_dec=0.9999 sgd_lambda=1e6
Training objective:9.00068e+07
Validation MRR: 0.169322
Training objective:9.00065e+07
Validation MRR: 0.171909
Training objective:9.00062e+07
Validation MRR: 0.172372
Training objective:9.0006e+07
Validation MRR: 0.172503
Training objective:9.00057e+07
Validation MRR: 0.172544
Training objective:9.00054e+07
Validation MRR: 0.172549
Prediction is computed in CLiMF as follows
reciproal_rank_ij = g( U_i ' * V_j )
where g() is the logistic function, and U_i is the feature vector of user i and V_j is the feature vector of user J. Both feature vectors are of size D.
The output of CLiMF are two files training_file_name_U.mm and training_file_name_V.mm.
Post processing of the output
Example 1: Load output in Matlab, for computing recommendations for ALS/SGD/NMF
a) run ALS ./toolkits/collaborative_filtering/als training=smallnetflix_mm validation=smallnetflix_mme lambda=0.065 minval=1 maxval=5 max_iter=6 quiet=1
b) download the script mmread.m.
c) # matlab
>> A=mmread('smallnetflix_mm');
>> U=mmread('smallnetflix_mm_U.mm');
>> V=mmread('smallnetflix_mm_V.mm');
>> whos
Name Size Bytes Class Attributes
A 95526x3561 52799104 double sparse
U 95526X5 3821040 double
V 3561X5 142480 double
c) compute prediction for user 8 movie 12:
>> U(8,:)*V(12,:)'
d) compute approximation error
c) compute prediction for user 8 movie 12:
>> U(8,:)*V(12,:)'
d) compute approximation error
>> norm(AU*V') % may be slow... depending on problem size
Example 2: Load output in Matlab, for verifying biasSGD results
a) run the command line:./toolkits/collaborative_filtering/biassgd training=smallnetflix_mm validation=smallnetflix_mme biassgd_lambda=1e4 biassgd_gamma=1e4 minval=1 maxval=5 max_iter=6 quiet=1
b) download the script mmread.m.
c) # matlab
>> V=mmread('smallnetflix_mm_V.mm'); % read item matrix V
>> U=mmread('smallnetflix_mm_U.mm'); % read user matrix U
>> m=mmread('smallnetflix_mm_global_mean.mm '); % read global mean
>> bV=mmread('smallnetflix_mm_V_bias.mm'); % read user bias
>> bU=mmread('smallnetflix_mm_U_bias.mm'); % read item bias
>> pairs = load('pairs'); % read user/item pairs
>> A=mmread('smallnetflix_mme'); % read rating matrix
>>
>> rmse = 0;
>> for r=1:545177, % run over each rating
% compute biasSGD prediction
% using the prediction rule:
% prediction = global_mean + bias_user + bias_item + vector_user*vector_item
pred = m + bU(pairs(r,1)) + bV(pairs(r,2)) + U(pairs(r,1),:)*V(pairs(r,2),:)';
pred = min( 5, pred ); % truncate prediction [1,5]
pred = max( 1, pred );
obs = A( pairs(r,1), pairs(r,2) );
rmse = rmse + (pred  obs).^2; % compute RMSE by (observation
% prediction)^2
end
>>
>> sqrt( rmse/545177.0 ) % print RMSE
ans =
1.1239 % compare the training RMSE to g
% graphchi output
Computing topK recommendations
For computing top K recommendations out of the computed linear model, use the rating/rating2 commands. The following algorithms are supported: ALS, sparseALS, NMF, SGD, WALS, SVD++, biasSGD, CLiMF, SVD.
For ALS, SparseALS, NMF, SGD,CliMF, SVD use rating application.
For SVD++, biasSGD, RBM use rating2 application.
For ALS, SparseALS, NMF, SGD,CliMF, SVD use rating application.
For SVD++, biasSGD, RBM use rating2 application.
First you need to run one of the above methods (ALS, SGD, NMF etc.) . Next, compute recommended ratings as follows:
./toolkits/collaborative_filtering/rating training=smallnetflix_mm num_ratings=5 quiet=1 algorithm=als
WARNING: common.hpp(print_copyright:128): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[num_rating] => [5]
[quiet] => [1]
Computing recommendations for user 1 at time: 0.827547
Computing recommendations for user 1001 at time: 0.871366
Computing recommendations for user 2001 at time: 0.908017
...
Computing recommendations for user 95001 at time: 2.15397
Rating output files (in matrix market format): smallnetflix_mm.ratings, smallnetflix_mm.ids
Distance statistics: min 0 max 42.1831 avg 9.51098
The output of the rating algorithm are two files. The first one is more useful.
1) filename.ids  includes recommended item ids for each user.
2) filename.ratings  includes scalar ratings of the top K items
bickson@thrust:~/graphchi/toolkits/collaborative_filtering$ head smallnetflix_mm.ids
%%MatrixMarket matrix array real general
%This file contains item ids matching the ratings. In each row i the top K item ids for user i. (First column is user id, next are top recommendations for this user).
95526 6
1 3424 1141 1477 2151 2012
2 2784 1900 516 1835 1098
3 1428 3450 2284 2328 58
4 209 1073 3285 60 1271
5 132 1702 2575 1816 2284
6 2787 1816 3024 2514 985
7 3078 375 168 2514 2460
...
bickson@thrust:~/graphchi/toolkits/collaborative_filtering$ head smallnetflix_mm.ratings %%MatrixMarket matrix array real general
%This file contains user scalar rating. In each row i, K top scalar ratings of different items recommended for user i.
95526 6
1 7.726248219530e+00 7.321665743778e+00 7.023083603761e+00 7.008616274552e+00
2 6.670937980807e+001.222724647853e+01 1.162004403228e+01 1.144299819709e+01
3 1.133374751034e+01 1.061483854315e+017.497070438026e+00 7.187132667285e+00
4 6.686989429238e+00 6.550680427186e+00 6.542147872641e+001.158861203665e+01
5 9.885307642785e+00 9.045366124418e+00 8.801333430322e+00 8.713271980918e+00
... ...
%This file contains item ids matching the ratings. In each row i the top K item ids for user i. (First column is user id, next are top recommendations for this user).
95526 6
1 3424 1141 1477 2151 2012
2 2784 1900 516 1835 1098
3 1428 3450 2284 2328 58
4 209 1073 3285 60 1271
5 132 1702 2575 1816 2284
6 2787 1816 3024 2514 985
7 3078 375 168 2514 2460
...
bickson@thrust:~/graphchi/toolkits/collaborative_filtering$ head smallnetflix_mm.ratings %%MatrixMarket matrix array real general
%This file contains user scalar rating. In each row i, K top scalar ratings of different items recommended for user i.
95526 6
1 7.726248219530e+00 7.321665743778e+00 7.023083603761e+00 7.008616274552e+00
2 6.670937980807e+001.222724647853e+01 1.162004403228e+01 1.144299819709e+01
3 1.133374751034e+01 1.061483854315e+017.497070438026e+00 7.187132667285e+00
4 6.686989429238e+00 6.550680427186e+00 6.542147872641e+001.158861203665e+01
5 9.885307642785e+00 9.045366124418e+00 8.801333430322e+00 8.713271980918e+00
... ...
Command line arguments
Basic configuration  training  (Mandatory) Input file name (in sparse matrix market format) for training data 
num_ratings  (Mandatory) Number of top items to recommend  
knn_sample_percent  (optional) A value between (0,1]. When the dataset is big and there are a lot of user/item pairs it may not be feasible to compute all possible pairs. knn_sample_percent tells the program how many pairs to sample  
minval  Truncate allowed ratings in range (optional)  
maxval  Truncate allowed ratings in range (optional)  
quiet  Less verbose (optional)  
algorithm  (Mandatory) The type of algorithm output for which the top K ratings are computed. For rating application the following algorithms are supported: als,sparse_als,nmf,sgd,wals For rating2 application: svd++,biassgd,rbm. For example algorithm=als  
start_user  (optional) Limit the rating computed starting from start_user (including)  
end_user  (optional) Limit the rating computed ending by end_user (not including) 
The rating command does not support yet all algorithms. Contact me if you like to add additional algorithms.
Handling implicit ratings
Implicit rating handles the case where we have only positive examples (for example when a user bought a certain product) but we never have indication when a user DID NOT buy another product. The paper [Pan, Yunhong Zhou, Bin Cao, Nathan N. Liu, Rajan Lukose, Martin Scholz, and Qiang Yang. 2008. OneClass Collaborative Filtering. In Proceedings of the 2008 Eighth IEEE International Conference on Data Mining (ICDM '08). IEEE Computer Society, Washington, DC, USA, 502511. ] proposes to add negative examples at random for unobserved user/item pairs. Implicit rating is implemented in the collaborative filtering library and can be used with any of the algorithms explained above.Basic configuration  implicitratingtype=1  Adds implicit ratings at random 
implicitratingpercentage  A number between 1e8 to 0.8 which determines what is the percentage of edges to add to the sparse model. 0 means none while 1 means fully dense model.  
implicitratingvalue  The value of the rating added. On default it is zero, but you can change it.  
implicitratingweight  Weight of the implicit rating (for WALS) OR Time of the explicit rating (for tensor algorithms) 
Example for implicit rating addition:
./toolkits/collaborative_filtering/sgd training=smallnetflix_mm implicitratingtype=1 implicitratingvalue=1 implicitratingpercentage=0.00001
WARNING: sgd.cpp(main:182): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[implicitratingtype] => [1]
[implicitratingvalue] => [1]
[implicitratingpercentage] => [0.00001]
INFO: sharder.hpp(start_preprocessing:164): Started preprocessing: smallnetflix_mm > smallnetflix_mm.4B.bin.tmp
INFO: io.hpp(convert_matrixmarket:190): Starting to read matrixmarket input. Matrix dimensions: 95526 x 3561, nonzeros: 3298163
INFO: implicit.hpp(add_implicit_edges:71): Going to add: 3401 implicit edges.
INFO: implicit.hpp(add_implicit_edges:79): Finished adding 3401 implicit edges.
WARNING: sgd.cpp(main:182): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[implicitratingtype] => [1]
[implicitratingvalue] => [1]
[implicitratingpercentage] => [0.00001]
INFO: sharder.hpp(start_preprocessing:164): Started preprocessing: smallnetflix_mm > smallnetflix_mm.4B.bin.tmp
INFO: io.hpp(convert_matrixmarket:190): Starting to read matrixmarket input. Matrix dimensions: 95526 x 3561, nonzeros: 3298163
INFO: implicit.hpp(add_implicit_edges:71): Going to add: 3401 implicit edges.
INFO: implicit.hpp(add_implicit_edges:79): Finished adding 3401 implicit edges.
...
Computing test predictions
It is possible to compute test predictions: namely entering a list of user / movie pairs and getting predictions for each item in the list. For creating such a list, create a sparse matrix market format file with the user/movie pair list in each row (and for the unknown prediction put a zero or any other number).Here is an example for generating predictions on the user/movie pair list on Netflix data:
bickson@thrust:~/graphchi$ ./toolkits/collaborative_filtering/biassgd training=smallnetflix_mm validation=smallnetflix_mme test=smallnetflix_mme quiet=1WARNING: biassgd.cpp(main:210): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[validation] => [smallnetflix_mme]
[test] => [smallnetflix_mme]
[quiet] => [1] 0.726158)
Iteration: 0 Training RMSE: 1.40926 Validation RMSE: 1.1636 1.61145) Iteration: 1 Training RMSE: 1.07647 Validation RMSE: 1.09299 2.536) Iteration: 2 Training RMSE: 1.02413 Validation RMSE: 1.05944 3.41652) Iteration: 3 Training RMSE: 0.996051 Validation RMSE: 1.03869 4.29683) Iteration: 4 Training RMSE: 0.977975 Validation RMSE: 1.02426 5.15537) Iteration: 5 Training RMSE: 0.965243 Validation RMSE: 1.01354
Finished writing 545177 predictions to file: smallnetflix_mme.predict
The input user/movie pair list is specified using the test=filename command.
The output predictions is found in the file smallnetflix_mme.predictions:
bickson@thrust:~/graphchi$ head smallnetflix_mme.predict
%%MatrixMarket matrix coordinate real general
%This file contains user/item pair predictions. In each line one prediction. The first column is user id, second column is item id, third column is the computed prediction.
95526 3561 545177
135 1 3.6310739
140 1 3.7827248
141 1 3.5731169
154 1 3.9835398
162 1 3.9378759
167 1 3.9865881
169 1 3.6489052
171 1 4.0544691
...
Speeding up execution
0) Verify that your program is compiled using the "O3" compiler flag. (Should be enabled on default). This gives significant speedup (for example x5). Verify that your program is compiled using EIGEN_NDEBUG compiler flag. (Should be enabled on default).1) If your system has enough memory, you can preload the problem into memory instead of reading them from disk on each iteration. This is done using the nshards=1 command.
This gives around x2 speedup.
2) If your system has enough memory, you can increase used memory size using the membudget_mb command. Example:
./toolkits/collaborative_filtering/als training=smallnetflix_mm validation=smallnetflix_mme lambda=0.065 minval=1 maxval=5 max_iter=6 quiet=1 membudget_mb 20000
3) You can tune the number of execution threads using execthreads command.
Depends on your machine different number of threads may give better results. The thumb rule is one thread per physical core.
Example for setting the number of threads:
./toolkits/collaborative_filtering/als training=smallnetflix_mm validation=smallnetflix_mme lambda=0.065 minval=1 maxval=5 max_iter=6 quiet=1 execthreads 4
4) You can disable compression by defining the following macro in your program code:
#define GRAPHCHI_DISABLE_
and recompiling. This will require increased disk space but will speed up execution.
KFold cross validation
It is possible to apply Kfold cross validation to your dataset. This is done by applying the following two flags:
kfold_cross_validation=10, enables kfold cross validation by setting K=10 and so on.
kfold_cross_validation_index=3, defines that we are working on the 4th fold (out of 10, indices start from zero).
Notes:
1) Currently supported algorithms for kfold cross validation are: als, wals, sparse_als, svdpp, nmf, pmf, sgd, biassgd, biassgd2, rbm, timesvdpp, baseline.
2) Selection is done by rows, so when using K=10, index=3 every 4th row in 10 rows will be excluded from the training set.
Example run:
./toolkits/collaborative_filtering/als training=smallnetflix_mm kfold_cross_validation=10 quiet=1 kfold_cross_validation_index=3 
WARNING: common.hpp(print_copyright:149): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[kfold_cross_validation] => [10]
[quiet] => [1]
[kfold_cross_validation_index] => [3]
[validation] => [smallnetflix_validation]
...
4.91313) Iteration: 0 Training RMSE: 2.03244 Validation RMSE: 1.19777
6.33828) Iteration: 1 Training RMSE: 0.748826 Validation RMSE: 1.15937
7.8193) Iteration: 2 Training RMSE: 0.690095 Validation RMSE: 1.14381
9.25151) Iteration: 3 Training RMSE: 0.665744 Validation RMSE: 1.13516
10.6588) Iteration: 4 Training RMSE: 0.649499 Validation RMSE: 1.13151
12.0984) Iteration: 5 Training RMSE: 0.638833 Validation RMSE: 1.13044
Finished writing 329816 predictions to file: smallnetflix_mm.predict
Now run for a different fold:
./toolkits/collaborative_filtering/als training=smallnetflix_mm kfold_cross_validation=10 quiet=1 kfold_cross_validation_index=4 validation=smallnetflix_validation
WARNING: common.hpp(print_copyright:149): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[kfold_cross_validation] => [10]
[quiet] => [1]
[kfold_cross_validation_index] => [4]
[validation] => [smallnetflix_validation]
...
4.7885) Iteration: 0 Training RMSE: 1.97529 Validation RMSE: 1.19191
6.11275) Iteration: 1 Training RMSE: 0.745336 Validation RMSE: 1.15712
7.52895) Iteration: 2 Training RMSE: 0.685904 Validation RMSE: 1.14291
8.91787) Iteration: 3 Training RMSE: 0.661709 Validation RMSE: 1.13662
10.2528) Iteration: 4 Training RMSE: 0.646958 Validation RMSE: 1.13445
11.5109) Iteration: 5 Training RMSE: 0.637327 Validation RMSE: 1.13369
Other cost functions
Most of the algorithms compute RMSE by default. We also support MAP@K metric. You can run it using the calc_ap=XX flag. The ap_number=XX flag defines K.Note: the assumption is that the dataset has binary values (0/1).
Common errors and their meaning
File not found error:
bickson@thrust:~/graphchi$ ./bin/example_apps/matrix_factorization/als_vertices_inmem file smallnetflix_mm
INFO: sharder.hpp(start_preprocessing:164): Started preprocessing: smallnetflix_mm > smallnetflix_mm.4B.bin.tmp
ERROR: als.hpp(convert_matrixmarket_for_ALS:153): Could not open file: smallnetflix_mm, error: No such file or directory
Solution:
Input file is not found, repeat step 5 and verify the file is in the right folder
Environment variable error:
bickson@thrust:~/graphchi/bin/example_apps/matrix_factorization$ ./als_vertices_inmem
ERROR: Could not read configuration file: conf/graphchi.local.cnf
Please define environment variable GRAPHCHI_ROOT or run the program from that directory.
Solution:
export GRAPHCHI_ROOT=/path/to/graphchi/folder/
Error:
FATAL: io.hpp(convert_matrixmarket:169): Failed to read global mean from filesmallnetflix_mm.gm
Solution: remove all temporary files created by the preprocessor, verify you have write permissions to your working folder and try again.
Adding fault tolerance
For adding fault tolerance, use the command line flag load_factors_from_file=1 when continuing any previous run.
The following algos are supported: ALS, WALS, sparse_ALS, tensor_ALS, NMF, SGD, biasSGD and SVD++.
Here is an example for biasSGD.
1) Run a few rounds of the algo:
bickson@thrust:~/graphchi$ ./toolkits/collaborative_filtering/biassgd training=smallnetflix_mm max_iter=3 quiet=1
WARNING: biassgd.cpp(main:210): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[max_iter] => [3]
[quiet] => [1]
1.5052) Iteration: 0 Training RMSE: 1.40926 Validation RMSE: 1.1636
3.30333) Iteration: 1 Training RMSE: 1.07647 Validation RMSE: 1.09299
5.28362) Iteration: 2 Training RMSE: 1.02413 Validation RMSE: 1.05944
=== REPORT FOR biassgdinmemoryfactors() ===
..
2) Now continue from the same run, after the 3 iterations:
bickson@thrust:~/graphchi$ ./toolkits/collaborative_filtering/biassgd training=smallnetflix_mm max_iter=3 quiet=1 load_factors_from_file=1
WARNING: biassgd.cpp(main:210): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[max_iter] => [3]
[quiet] => [1]
[load_factors_from_file] => [1]
2.63894) Iteration: 0 Training RMSE: 0.996053 Validation RMSE: 1.03869
4.07894) Iteration: 1 Training RMSE: 0.977975 Validation RMSE: 1.02427
5.6297) Iteration: 2 Training RMSE: 0.965245 Validation RMSE: 1.01355
..
As you can see the second runs, starts from the state of the first run.
Item based similarity methods
Item based similarity methods documentation is found here.
Case studies
ACM KDD CUP 2012  in this post I show how to utilize multiple feature information for predicting advertisement clicked by users, using KDD CUP 2012 data (we won 4th place out of 192 groups).
Airline on time dataset + Hearst machine learning challenge  in this post I show how to predict airplane flight time using airline on time dataset, and how to predict user reaction to email campaign using the hearst machine learning challenge.
ACM KDD CUP 2010  in this post I explain how to predict student learning abilities using ACM KDD CUP 2010 dataset.
Million songs dataset  in this post I explain how to obtain the winning solution in the millions songs dataset contest, using a computation of item based similarities and their derived recommendaitons.
Million songs dataset  in this post I explain how to obtain the winning solution in the millions songs dataset contest, using a computation of item based similarities and their derived recommendaitons.
Acknowledgements/ Hall of Fame
Deployment of GraphChi CF toolkit was not possible without the great help of data scientist around the world who contributed their efforts for improving my code! Here is a preliminary list, I hope I did not forget anyone...
 Liang Xiong, CMU for providing the Matlab code of BPTF, numerous discussions and infinite support!! Thanks!!
 Timmy Wilson, Smarttypes.org for providing twitter network snapshot example, and Python scripts for reading the output.
Sanmi Koyejo, from the University of Austin, Texas, for providing Python scripts for preparing the inputs.
Dan Brickely, from VU University Amsertdam, for helping debugging installation and prepare the input in Octave.
Nicholas Ampazis, University of the Aegean, for providing his SVD++ source ode.
Yehuda Koren, Yahoo! Research, for providing his SVD++ source code implementation.
Marinka Zitnik, University of Ljubljana, Slovenia, for helping debugging ALS and suggesting NMF algos to implement.
Joel Welling from Pittsburgh Supercomputing Center, for optimizing GraphLab on BlackLight supercomputer and simplifying installation procedure.
Sagar Soni from Gujarat Technological University and Hasmukh Goswami College of Engineering for helping testing the code.
Young Cha, UCLA for testing the code.
Mohit Singh for helping improve documentation.
Nicholas Kolegraff for testing our examples.
Theo Throuillon, Ecole Nationale Superieure d'Informatique et de Mathematiques Appliquees de Grenoble for debugging NMF.
Qiang Yan, Chinese Academy of Science for providing timesvd++, biasSVD, RBM and LIBFM code that the Graphlab/GraphChi version is based on.
Ramakrishnan Kannan, Georgia Tech, for helping debugging and simplifying usage.
Charles Martin, GLG, for debugging NMF.  Izhar Wallach, University of Toronoto, for debugging biasSGD.
 Aleksandr Krushnyakov, Moscow State University, for debugging GraphCHi CF package
 Alessandro Vitale, Optimist AI SRL, for detecting a bug in item based cf
 Jacob Kesinger, quid.com, for reporting a bug in item based cf
 Jason Chao, Douban.com, for numerous bug reports and fixes.
 James Curnalia, Graduate student @ Youngstown State University for submitting bug reports.
 Brad Cox, Technica, for bug reporting!
 Andrea Cervellin, Leiden University, for SVD++ testing and bug reports.
 ChungYi Li, National Taiwan University, for PMF bug report.
 Clive Cox, Rummble Labs, for numerous contributions including Aiolli's metric code in item based CF.
 Murat Can Cobanoglu, CMU and University of Pittsburgh, for bug report.
 Mohammad Burhan, Fraunhofer IAIS, for compilation bug report
 Sergey Nikolenko, Adjunct Professor, Academic University, St. Petersburg for submitting compilation patch.
 Tsz Hing Lau (Anson), City University of Hong Kong, for debugging GraphChi on windows+ virtual box + ubuntu.
 Richard Oentaryo, Singapore Management University, for fixing libFM bug.
 Mark Levy, lib.fm, for contributing CLiMF algorithm.
 Matt Aldrich, MIT Media Lab, for debugging GraphChi output.
 Curtis Qingwei Ge, grad student, University of Toronto, for bug fix to pmf
Hi Danny,
ReplyDeleteThe link to mmread.m is broken, how ever I did a little snooping and found it over here:
http://select.cs.cmu.edu/code/graphlab/mmread.m
Link fixed. Thanks!!
DeleteHello again! :)
ReplyDeleteThanks for your previous replies to my answers
I'm running examples with netflix data in .mm and .mme files.
So I'd like to know  what method results in 7) relate to?
1) I've run all methods ALS, SGD, biasSGD, SVD++ and NMF
It executed successfully.
But results in head of U_matrix doesn't match any results I've got.
2) Also I've tried to run WALS as it described in 6e)
but it failed like this:
FATAL: io.hpp(convert_matrixmarket:226): Col index larger than the matrix col size 3902 > 3561 in line; 701
terminate called after throwing an instance of 'char const*'
Aborted (core dumped)

Are results in 7) probably old ?
And how can I start WALS?
(BTW it's not essential for me to run WALS, i'm interesting mostly in working with SVD  but may be my notes will help you to fix some bugs :) )
Hi Aleksandr,
DeleteYou feedback is highly valuable. In fact, I have just added you an acknowledgement (send me a link to your website if you have one and I will link to it).
Regarding 7)  it explains how to read the output of the multiple methods.
I am not sure what you mean about results of the U_matrix? please elaborate.
Regarding WALS, please note that WALS takes 4 inputs in a row: [user] [item] [time/weight] [rating]. You need to download the files: http://www.select.cs.cmu.edu/code/graphlab/datasets/time_smallnetflix and
http://www.select.cs.cmu.edu/code/graphlab/datasets/time_smallnetflixe
Let me know if you have any additional questions!
I meant smallnetflix_mm_U.mm  when talked about U_matrix.
DeleteSo you made everything clear about it for me.
About WALS:
I have
smallnetflix_mm
smallnetflix_mme
and
time_smallnetflix
time_smallnetflixe
files in my /graphchi
And I'm trying just to execute 6e)
./toolkits/collaborative_filtering/als training=time_smallnetflix validation=time_smallnetflixe lambda=0.065 minval=1 maxval=5 max_iter=6 quiet=1
So I haven't understand details of inputs yet  I just try to follow instructions in 6e).
And it throws message that something goes wrong with sizes of matrices.
Am I doing smth wrong?
Now I got your source of confusion... 6e) was supposed to be wals and not als, I have no fixed documentation. Please try again.
DeleteThat time everything passed well, thank you!
Deletetaras@ubuntu:~/graphchi$ bash install.sh
ReplyDelete20121124 01:11:31 http://bitbucket.org/eigen/eigen/get/3.1.1.tar.bz2
Resolving bitbucket.org... 207.223.240.182, 207.223.240.181
Connecting to bitbucket.org207.223.240.182:80... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
Location: https://bitbucket.org/eigen/eigen/get/3.1.1.tar.bz2 [following]
20121124 01:11:31 https://bitbucket.org/eigen/eigen/get/3.1.1.tar.bz2
Connecting to bitbucket.org207.223.240.182:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1049447 (1,0M) [application/xbzipcompressedtar]
Saving to: `3.1.1.tar.bz2.2'
100%[==================================================================================================>] 1 049 447 634K/s in 1,6s
20121124 01:11:34 (634 KB/s)  `3.1.1.tar.bz2.2' saved [1049447/1049447]
mv: cannot move `eigeneigen43d9075b23ef/Eigen' to `./src/Eigen': Directory not empty
g++ g O3 I/usr/local/include/ I../../src/ I. fopenmp Wall Wnostrictaliasing als.cpp o als
In file included from common.hpp:32,
from als.cpp:56:
util.hpp: In constructor ‘in_file::in_file(std::string)’:
util.hpp:24: error: ‘LOG_FATAL’ was not declared in this scope
util.hpp:24: error: ‘logstream’ was not declared in this scope
In file included from ../../src/graphchi_basic_includes.hpp:51,
from common.hpp:33,
from als.cpp:56:
../../src/metrics/reps/file_reporter.hpp: In member function ‘virtual void graphchi::file_reporter::do_report(std::string, std::string, std::map, std::allocator >, graphchi::metrics_entry, std::less, std::allocator > >, std::allocator, std::allocator >, graphchi::metrics_entry> > >&)’:
../../src/metrics/reps/file_reporter.hpp:74: warning: format ‘%lu’ expects type ‘long unsigned int’, but argument 5 has type ‘size_t’
../../src/metrics/reps/file_reporter.hpp:82: warning: format ‘%lu’ expects type ‘long unsigned int’, but argument 5 has type ‘size_t’
In file included from common.hpp:37,
from als.cpp:56:
../../example_apps/matrix_factorization/matrixmarket/mmio.c: In function ‘int mm_write_mtx_crd_size(FILE*, uint, uint, size_t)’:
../../example_apps/matrix_factorization/matrixmarket/mmio.c:185: warning: format ‘%ld’ expects type ‘long int’, but argument 5 has type ‘size_t’
../../example_apps/matrix_factorization/matrixmarket/mmio.c: In function ‘int mm_read_mtx_crd_size(FILE*, uint*, uint*, size_t*)’:
../../example_apps/matrix_factorization/matrixmarket/mmio.c:207: warning: format ‘%ld’ expects type ‘long int*’, but argument 5 has type ‘size_t*’
..................
...............
/../src/engine/graphchi_engine.hpp: In member function ‘void graphchi::graphchi_engine::write_delta_log() [with VertexDataType = vertex_data, EdgeDataType = float, svertex_t = graphchi::graphchi_vertex]’:
../../src/engine/graphchi_engine.hpp:727: instantiated from ‘void graphchi::graphchi_engine::run(graphchi::GraphChiProgram&, int) [with VertexDataType = vertex_data, EdgeDataType = float, svertex_t = graphchi::graphchi_vertex]’
als.cpp:228: instantiated from here
../../src/engine/graphchi_engine.hpp:451: warning: format ‘%lu’ expects type ‘long unsigned int’, but argument 4 has type ‘size_t’
../../src/engine/graphchi_engine.hpp:451: warning: format ‘%lu’ expects type ‘long unsigned int’, but argument 5 has type ‘size_t’
make: *** [als] Error 1
Thanks Taras for your feedback! I have fixed the compilation error. Retake from mercurial using "hg pull; hg update" and recompile using "make clean; make cf".
DeleteLet me know if this works!
Thanks a lot! It works good now.
Delete~/graphchi$ bash install.sh
ReplyDelete20121205 16:50:09 http://bitbucket.org/eigen/eigen/get/3.1.1.tar.bz2
Resolving bitbucket.org (bitbucket.org)... 207.223.240.182, 207.223.240.181
Connecting to bitbucket.org (bitbucket.org)207.223.240.182:80... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
Location: https://bitbucket.org/eigen/eigen/get/3.1.1.tar.bz2 [following]
20121205 16:50:29 https://bitbucket.org/eigen/eigen/get/3.1.1.tar.bz2
Connecting to bitbucket.org (bitbucket.org)207.223.240.182:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1049447 (1,0M) [application/xbzipcompressedtar]
Saving to: `3.1.1.tar.bz2'
100%[======================================>] 1 049 447 781K/s in 1,3s
20121205 16:50:31 (781 KB/s)  `3.1.1.tar.bz2' saved [1049447/1049447]
g++ g I/usr/local/include/ I../../src/ I. fopenmp Wall Wnostrictaliasing als.cpp o als
In file included from als.cpp:91:0:
rmse.hpp: In function ‘void test_predictions_N(float (*)(const vertex_data**, int, float, double&), int, int*, bool*, int, bool)’:
rmse.hpp:241:47: error: ‘minarray’ was not declared in this scope
rmse.hpp: In function ‘void validation_rmse_N(float (*)(const vertex_data**, int, float, double&), graphchi::graphchi_context&, int, int, int*, float*, bool*, int, bool)’:
rmse.hpp:486:42: error: ‘struct vertex_data’ has no member named ‘last_item’
make: *** [als] Error 1
Sorry about that  I committed some experimental code. Please retake again from mercurial using (hg pull; hg update) and then recompile using (make clean; make).
DeleteBest,
I am experiencing the same compilation errors that Taras reported earlier. However, updating has failed to resolve the issue. Are there any any additional resources which may be necessary (I'm using a virtual machine running a new install of Ubuntu 12.10).
ReplyDeleteVery strange.. I just compiled a few minutes ago and everything is smooth..
DeleteAre you checking out from mercurial?
Please checkout using hg pull; hg update
and then recompile using make clean; make cf.
If you still have an error please send me the output..
OOPS... Just found another error. Fixed it. Please retry.
DeleteThe update you just posted seems to have fixed everything.
DeleteA completely unrelated question, is it possible to chain the outputs of the algorithms in order to further refine the accuracy?
It is not possible to compute blending or some ensemble method to join together several solutions for higher accuracy. This is a feature we may add in the future.
DeleteIt is possible, to load factors from previous run of the same algorithms from disk and continue from the previous run results in order to refine them. This is done using the load_factors_from_file=1 flag. See example in the section "adding fault tolerance".
I was hoping to use ensemble methods. I look forward to the capability.
DeleteI am expecting that "filename.ids  includes recommended item ids for each user." will contain k recommendations defined by num_ratings. For example when num_ratings = 3, then for each customer recommend 3 items. If this is the case then I am experiancing 10 recommendation everytime. Is that a bug?
ReplyDeleteIt should be num_ratings (and not num_rating). please try again!
DeleteThanks, it is working now :)
Delete1. Note: for weightedALS, the input file has 4 columns:
ReplyDelete[user] [item] [weight] [rating]. See example file in section 5b).
> I think it is 5e rather than 5b.
2. For weightedALS use the rating4 command
> There is no rating4 command /toolkits/collaborative_filtering/
Thanks for the update. I have fixed the documentation.
DeleteHi Danny,
ReplyDeleteI getting the following error while I am executing the recommendatation based on WALS.
FATAL: chifilenames.hpp(get_shard_edata_filesize:115): Could not load /time_smallnetflix.edata.e8B.0_3.size. Preprocessing forgotten?
terminate called after throwing an instance of 'char const*'
Aborted
As mentioned, I have followed the following steps
step1: ./wals training=/time_smallnetflix validation=/time_smallnetflixe lambda=0.065 minval=1 maxval=5 max_iter=10 quiet=1
step2: ./rating training=/home/kamesh/input/reco/time_smallnetflix tokens_per_row=4 num_ratings=5 quiet=1
While step1 was always sucessed, but was failing when I am trying to execute the step2.
Please help me, where am I doing mistake?
Thanks for your bug report  I have now fixed this. Please retake from mercurial and let me know if this works for you. (using "hg pull; hg update ; make clean ; make cf")
DeleteBest,
Hi Danny,
DeleteThanks, It is working now
Hi Danny,
ReplyDeleteI am working on installing GraphChi on centos vm 6.3 and encountering following error.
als.cpp:214: instantiated from here
../../src/util/ioutil.hpp:157: error: ‘deflateInit’ was not declared in this scope
../../src/util/ioutil.hpp:174: error: ‘deflate’ was not declared in this scope
../../src/util/ioutil.hpp:178: error: ‘deflateEnd’ was not declared in this scope
../../src/util/ioutil.hpp:188: error: ‘deflateEnd’ was not declared in this scope
make[1]: *** [als] Error 1
make[1]: Leaving directory `/home/romit/graphchi/toolkits/collaborative_filtering'
1) Please try to check out from mercurial  this error should be fixed now. (I assume you downloaded the tgz source file.
Delete2) If it does not help, please send me the full compilation command line and the full output so I could look at it. But checking from mercurial should fix it.
Hi Danny,
ReplyDeleteI have two questions.
For weightedALS, the input file has 4 columns i.e,
[user] [item] [weight] [rating]
where [weight] is the frequency of click through on items?
if that is true, suppose an item was never bought but it was viewed many times hence it will have no rating. in that case the data file will be like [user] [item] [weight] 0?
regards,
Burhan
There may be more than one correct way to map between your problem into a matrix factorization problem. weight may be the number of clicks or frequency of clicks  you should try both and see which works better.
DeleteRegarding zeros  it is not recommended to use zero rating. I suggest trying 1 for viewed and 2 for purchased.
Danny
DeleteI'm dealing with a one class problem too and i'm not sure i clearly understood your answer.
From what i understand of "[Pan, Yunhong Zhou, Bin Cao, Nathan N. Liu, Rajan Lukose, Martin Scholz, and Qiang Yang. 2008. OneClass Collaborative Filtering.", they add 0 in the matrix giving them a weight considering a specific measure.
In the case of a product i would say that the inverse of click would be a good weight for these zero (meaning that the more a person click on a product the less the 0 is likely to be true).
Without weight, i would put 2, 1 and 0 to the products bought, seen and nothing.
I don't undesrtand why it's not recommended to use zero rating in this specific case (i think i saw you use 1/1 in a classification probleme in one of your example)?
Would you use "WALS + 1 for viewed and 2 for purchased" ?
Regards.
Hi Alex,
DeleteYou are of course right, they use zero in their paper. What confused me is that for the zero case you should specify minval=0 and maxval=1 namely allowed predictions should be truncated between [0,1]. (And not minval=1 and maxval=1 as appeared in the question).
The problem with zeros, is that you can not differentiate between zero which is a missing value, to a known zero rating. That is why in many cases we use 1 as negative rating and 1 as positive rating.
Let me know if this is clearer..
Danny,
ReplyDelete"(And not minval=1 and maxval=1 as appeared in the question)." => do you talk about Burhan's question or Venkata siva's one ?
"The problem with zeros, is that you can not differentiate between zero which is a missing value, to a known zero rating." => that part is still not clear, maybe there's something i've missed about the graph representation of data.
If i add implicit ratings with 0 value to my one class data, i'll get a matrix filled with 1 (positive ratings), 0 (negative ratings) and missing values, in my mind i would not get 0 corresponding to missing values.
Do you mean that graphchi will add edge with 0 value coresponding to missing value in addition to the implicit ratings ?
To be clearer, in a one class problem, if i use this command :
./toolkits/collaborative_filtering/biassgd2 training=xxx implicitratingtype=1 implicitratingvalue=1 implicitratingpercentage=0.00001 minval=1 maxval=1
will i get a different result (i mean rank of product not ratings) than this one :
./toolkits/collaborative_filtering/biassgd2 training=xxx implicitratingtype=1 implicitratingvalue=0 implicitratingpercentage=0.00001 minval=0 maxval=1
In the graphlab user group you've answered to Venkata siva on the same subject : "I will add a sanity check that verifies you do not use implicit rating value of 0.", so i supposed there's a real problem of using 0 value implicit ratings ??!
Thanks in advance for your answer.
Regards.
Hi Alex,
DeleteSo many questions  I am starting to get confused.. :)
Some algorithm can support zero ratings, and some others can not. For example, when you solve a sparse linear system, there is no distinction between a zero coefficient or no coefficient. In ALS it is possible to have zero ratings, and the algorithm tries to minimize
the dot product between the matching factors and the zero rating. The same with SGD  it is possible to have zero rating.
My answer to Venkata about implicit rating value of zero is wrong  I will fix it  since zero is support in some of the algos.
Hi,
ReplyDeleteI am trying run WALS, but following links which you mentioned are not working.
http://select.cs.cmu.edu/code/graphlab/time_smallnetflix
This is the right link: http://select.cs.cmu.edu/code/graphlab/datasets/time_smallnetflix
DeleteThanks Danny.
DeleteIt's working now.
I have few queries, Can you please suggest me on these?
1) At present, Now I tuned lamda such that RMSE ~ 2. But how can I verify, whether reco's are correct are not? Is there any way to check correctness(like confusion matrix).
2) And also my requirement is to generate reco's based location. So can you please suggest me, which algorithm will fit for this?
There are many ways to evaluate the quality of recommendations. Take a look here
Deletefor a detailed list: http://bickson.blogspot.co.il/2012/10/the10recommendersystemmetricsyou.html
If you have the location of the user as one of the features, I suggest trying out gensgd:
http://bickson.blogspot.co.il/2012/12/collaborativefiltering3rdgeneration_14.html
Best,
Hi Danny,
ReplyDeleteGreat work!
I have a question about the implicitratingtype option. Pan et al.'s paper suggest 3 implicit rating types: uniform random, useroriented, and itemoriented. Am I right in assuming that only the first is implemented already?
Also, Pan et al.'s paper uses weighting to indicate how credible the training data is. It seems like this is not implemented in ALS itself, but after reading the papers it seems that WALS (by Hu et al.) is a generalization of this weighting, so I can just use WALS instead?
And one more thing: in the WALS paper, prediction is done by simply computing p_u * q_i (the latent user and item factors). Still, here it is stated that we should use
r_ui = w_ui * p_u * q_i. Why is this? Is this a result of this specific implementation?
Many thanks!
Joaquin
Thanks Joaquin!
DeleteYou are right  the uniform random is currently implemented.
You can use WALS if you want to have a confidence level/or weight for each rating.
Prediction is simply p_u * q_i. But when RMSE is computed than the square error is weighted by w_ui.
Best,
Thanks for the quick reply, Danny!
DeleteHi Danny,
ReplyDeleteCan you please provide some instructions about how to build this on windows.
I have tried the Java version but it doesn't include this great package (is there a plan to port it to Java version?)
I used Eclipse and MinGW to build on windows but got lots of errors . A brief description of the build process for windows (environment ,libraries etc) can save a lots of debugging time and make this great package available on windows .
If I want to install linux on my PC (dual boot) what version you recommend?
Sample erors from my build:
Description Resource Path Location Type
'pread' was not declared in this scope ioutil.hpp /graphchi/src/util line 44 C/C++ Problem
'pwrite' was not declared in this scope ioutil.hpp /graphchi/src/util line 89 C/C++ Problem
'random' was not declared in this scope stripedio.hpp /graphchi/src/io line 383 C/C++ Problem
'random' was not declared in this scope stripedio.hpp /graphchi/src/io line 705 C/C++ Problem
'S_IROTH' was not declared in this scope binary_adjacency_list.hpp /graphchi/src/preprocessing/formats line 194 C/C++ Problem
'S_IROTH' was not declared in this scope conversions.hpp /graphchi/src/preprocessing line 692 C/C++ Problem
'S_IROTH' was not declared in this scope graphchi_engine.hpp /graphchi/src/engine line 988 C/C++ Problem
'S_IROTH' was not declared in this scope ioutil.hpp /graphchi/src/util line 107 C/C++ Problem
'S_IROTH' was not declared in this scope sharder.hpp /graphchi/src/preprocessing line 256 C/C++ Problem
'S_IROTH' was not declared in this scope sharder.hpp /graphchi/src/preprocessing line 524 C/C++ Problem
'S_IROTH' was not declared in this scope sharder.hpp /graphchi/src/preprocessing line 665 C/C++ Problem
'S_IROTH' was not declared in this scope sharder.hpp /graphchi/src/preprocessing line 795 C/C++ Problem
'S_IROTH' was not declared in this scope sharder.hpp /graphchi/src/preprocessing line 846 C/C++ Problem
'S_IWOTH' was not declared in this scope binary_adjacency_list.hpp /graphchi/src/preprocessing/formats line 194 C/C++ Problem
'S_IWOTH' was not declared in this scope conversions.hpp /graphchi/src/preprocessing line 692 C/C++ Problem
'S_IWOTH' was not declared in this scope graphchi_engine.hpp /graphchi/src/engine line 988 C/C++ Problem
'S_IWOTH' was not declared in this scope ioutil.hpp /graphchi/src/util line 107 C/C++ Problem
'S_IWOTH' was not declared in this scope sharder.hpp /graphchi/src/preprocessing line 256 C/C++ Problem
'S_IWOTH' was not declared in this scope sharder.hpp /graphchi/src/preprocessing line 524 C/C++ Problem
'S_IWOTH' was not declared in this scope sharder.hpp /graphchi/src/preprocessing line 665 C/C++ Problem
'S_IWOTH' was not declared in this scope sharder.hpp /graphchi/src/preprocessing line 795 C/C++ Problem
'S_IWOTH' was not declared in this scope sharder.hpp /graphchi/src/preprocessing line 846 C/C++ Problem
make: *** [example_apps/connectedcomponents] Error 1 graphchi C/C++ Problem
there are no arguments to 'pread' that depend on a template parameter, so a declaration of 'pread' must be available [fpermissive] ioutil.hpp /graphchi/src/util line 44 C/C++ Problem
there are no arguments to 'pread' that depend on a template parameter, so a declaration of 'pread' must be available [fpermissive] ioutil.hpp /graphchi/src/util line 62 C/C++ Problem
there are no arguments to 'pwrite' that depend on a template parameter, so a declaration of 'pwrite' must be available [fpermissive] ioutil.hpp /graphchi/src/util line 89 C/C++ Problem
there are no arguments to 'random' that depend on a template parameter, so a declaration of 'random' must be available [fpermissive] graph_objects.hpp /graphchi/src/api line 292 C/C++ Problem
too many arguments to function 'int mkdir(const char*)' sharder.hpp /graphchi/src/preprocessing line 654 C/C++ Problem
I definitely did not target WIndows as a potential platform for my code :)
DeleteI suggest installing https://www.virtualbox.org/ with the latest ubuntu image and
you are ready to run on windows..
Hello Danny,
ReplyDeleteI am testing these collaborative filtering algorithms on my company data and the resulting predictions are pretty good.
However, the computed recommendations that I get after running a particular algorithm say, SGD on my static dataset are dynamic and different than the previous execution.
Can you tell me whether this is to be expected?
Thanks
Manu
Hi Manu,
DeleteI am not sure I got your question. How do you compute the predictions? Is this using the "rating" application, or do you read the matrices U and V and compute the required dot products? If you read U and V using your own program from file, please be careful, since we save the matrices by row order and not by column order.
Hi Danny,
DeleteI am performing the following steps:
1) I created the training file with user id, item id and rating on my dataset.
2) I ran SGD on the training file.
3) I then ran the command for computing predictions.
./toolkits/collaborative_filtering/rating training=hit_mm num_ratings=10 quiet=1
Now, the file "hit_mm".ids that is being created has the 10 item recommendations corresponding to each user.
When I repeat the steps 2 and 3 on the same training file(no changes are made in it), the "filename.ids" created this time has different item ids corresponding to each customer.
Thus, the item recommendations for the customers generated are different each time even though I have not changed the training file data.
I wanted to get the top 10 recommendations for each user but each time the items recommended are different for the user even though SGD algorithm followed by the computing recommendation command is being run on the same dataset.
Thanks,
Manu
This can only be the case if there are several items which gets exactly the same score  in that case you can get a different ordering of them each time. Can you check the ratings file to verify if this is the case?
DeleteIf you suspect some bug, please prepare a small training file were this error happens and send me the file along with the exact command line arguments you are using so I can look at it. And please send it to our user mailing list: graphlabkdd@groups.google.com
Hi Danny,
DeleteThe recommendations are different even when I run the smallnetflix_mm example as explained above.
I run the following steps:
1) ./toolkits/collaborative_filtering/baseline training=smallnetflix_mm validation=smallnetflix_mm minval=1 maxval=5 quiet=1 algorithm=user_mean
2) ./toolkits/collaborative_filtering/sgd training=smallnetflix_mm validation=smallnetflix_mme sgd_lambda=1e4 sgd_gamma=1e4 minval=1 maxval=5 max_iter=6 quiet=1
3) ./toolkits/collaborative_filtering/rating training=smallnetflix_mm num_ratings=5 quiet=1
The smallnetflix_mm file is having different recommendations generated each time when i repeat the steps. The scalar ratings for the items in the smallnetflix.ratings is different for all items.
It might be that i am missing some steps. Here, I am listing the item ids generated for first 3 customers for the smallnetflix file using abobe commands.
Iteration 1:
95526 6
1 2385 1871 2153 512 2024
2 444 3285 512 3141 3557
3 3285 444 1872 1075 1871
Iteration 2:
95526 6
1 3298 3290 1704 3271 717
2 3290 8 3271 3215 931
3 3298 535 1996 646 2053
Thanks,
Manu
Hi Manu,
DeleteThanks for our note. I now get your question.
SGD starts at a random states and computes a gradient descent starting from this state. Thus each run starts from a different state. Furthermore, running 5 iterations does not get the algorithm into a local minima (you can learn about it that RMSE still goes down and does not converge), thus it makes sense that each different run results in a different recommendation.
I assume that once you run the algorithm for enough iterations, hopefully the algorithm converge to some significant local minima, and in that case you will see some repeating items recommended that are more "dominent".
From the other hand, if you will run the command rating twice from the same state, you will get the exact same recommendation. You can try it out.
If you use the load_factors_from_file=1 flag, you can force SGD to start from a specific initial state, and in this case, most chances you will get similar result (up to some randomness induced by parallelization of the computation).
Hi Danny,
DeleteThank You for the explanation.
I tried it after increasing the iteration for the "smallnetflix" example. I am getting some repeating items for it.
In the case of my company dataset, I am not getting repeating items after increasing the interations. I would try to force SGD to start from a initial state.
Thanks,
Manu
Hi Danny,
DeleteI executed my dataset 4 differnt times with ALS algorithm having 100 iterations each. The data that is being returned now contains some commen items in each execution. However, the common item being recommended is not good recommendation.
It is as I think because the ratings are only a handful and the matrix is very sparse.
Should I try using WALS in highly sparse matrix cases with weightage based on whether item was viewed, put in cart or purchased.
Thanks,
Manu
It that case, I recommended not to merge the different features into a single scalar (viewed, put in cart, purchased) but to use gensgd: http://bickson.blogspot.co.il/2012/12/collaborativefiltering3rdgeneration_14.html with all the different features for getting a more accurate prediction.
DeleteHi Danny,
ReplyDeleteI'm getting the following error while running WALS:
ERROR: chifilenames.hpp(load_vertex_intervals:364): Could not load intervalsfile: /Users/joa/Documents/ProjectX/View_graphchie.2.intervals
The strange thing is that if I run it a second time, it works fine. It seems that you are expecting a file that isn't (yet?) available, but the second time around it does find that file (generated by the previous run?).
This is on a mac, the command used is wals with options minval=0 maxval=1 max_iter=2 quiet=1 implicitratingtype=1 D=20 lambda=0.02
Thanks,
Joaquin
It seems that you local binary cache file we use for GraphChi got garbled. Please remove all intermediate files using the command "rm fR filename.*" where filename is your training input file, and the same for your validation input file.
DeleteRight, that solved the issue. Thanks Danny!
DeleteHi Danny,
ReplyDeleteDoes the package raphchi_src_v0.2.1.tar.gz
supposed to include zlib header files? If yes why zlib.h is missing when I try to install?
I dowloaded the file graphchi_src_v0.2.1.tar.gz
when trying to install on ubuntu (using bash install.sh) I get the folllowing error:
../../src/util/ioutil.hpp:35:18: fatal error: zlib.h: No such file or directory
thanks for your help
Al
Now GraphChi has zlib dependency you should install it in your ubuntu using:
Deletesudo aptget install zlib1g zlib1gdev
I did that and it worked.
ReplyDeleteThank you very much.Al
Hi,Danny
ReplyDeleteI tried to apply SVD++ in GraphChi to my own dataset, but got training RMSE larger than baseline with user mean algorithm. And most predicted results are 1.
So I tested it with smallnetflix_mm dataset. And I got this:
./toolkits/collaborative_filtering/svdpp training=smallnetflix_mm biassgd_lambda=1e4 biassgd_gamma=1e4 minval=1 maxval=5 max_iter=40 quiet=1
[training] => [smallnetflix_mm]
[biassgd_lambda] => [1e4]
[biassgd_gamma] => [1e4]
[minval] => [1]
[maxval] => [5]
[max_iter] => [40]
[quiet] => [1]
5.76351) Iteration: 0 Training RMSE: 1.85505
11.39) Iteration: 1 Training RMSE: 1.88477
17.0008) Iteration: 2 Training RMSE: 1.88162
22.615) Iteration: 3 Training RMSE: 1.88363
28.2434) Iteration: 4 Training RMSE: 1.8801
33.8473) Iteration: 5 Training RMSE: 1.8806
39.4943) Iteration: 6 Training RMSE: 1.87717
45.1257) Iteration: 7 Training RMSE: 1.87193
50.735) Iteration: 8 Training RMSE: 1.87877
56.3461) Iteration: 9 Training RMSE: 1.86998
61.9751) Iteration: 10 Training RMSE: 1.87939
67.6264) Iteration: 11 Training RMSE: 1.87873
73.2331) Iteration: 12 Training RMSE: 1.88215
78.8441) Iteration: 13 Training RMSE: 1.88339
84.4545) Iteration: 14 Training RMSE: 1.89403
90.0751) Iteration: 15 Training RMSE: 1.89794
95.6995) Iteration: 16 Training RMSE: 1.90168
101.32) Iteration: 17 Training RMSE: 1.91386
106.934) Iteration: 18 Training RMSE: 1.92345
112.56) Iteration: 19 Training RMSE: 1.93437
118.195) Iteration: 20 Training RMSE: 1.94366
123.813) Iteration: 21 Training RMSE: 1.94866
129.443) Iteration: 22 Training RMSE: 1.9549
135.067) Iteration: 23 Training RMSE: 1.96029
140.674) Iteration: 24 Training RMSE: 1.96464
146.3) Iteration: 25 Training RMSE: 1.96941
151.912) Iteration: 26 Training RMSE: 1.97312
157.527) Iteration: 27 Training RMSE: 1.97665
163.143) Iteration: 28 Training RMSE: 1.97978
168.76) Iteration: 29 Training RMSE: 1.98246
174.379) Iteration: 30 Training RMSE: 1.98439
179.983) Iteration: 31 Training RMSE: 1.9872
185.603) Iteration: 32 Training RMSE: 1.98911
191.245) Iteration: 33 Training RMSE: 1.99011
196.871) Iteration: 34 Training RMSE: 1.99117
202.475) Iteration: 35 Training RMSE: 1.99125
208.098) Iteration: 36 Training RMSE: 1.99237
213.719) Iteration: 37 Training RMSE: 1.99255
219.332) Iteration: 38 Training RMSE: 1.99185
224.951) Iteration: 39 Training RMSE: 1.99234
Do you have any idea what is the problem?
Something is wrong.. I run the same command and I get:
Deletebickson@thrust:~/graphchi$ ./toolkits/collaborative_filtering/svdpp training=smallnetflix_mm biassgd_lambda=1e4 biassgd_gamma=1e4 minval=1 maxval=5 max_iter=40 quiet=1
WARNING: common.hpp(print_copyright:139): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[biassgd_lambda] => [1e4]
[biassgd_gamma] => [1e4]
[minval] => [1]
[maxval] => [5]
[max_iter] => [40]
[quiet] => [1]
1.41124) Iteration: 0 Training RMSE: 1.18431
2.6689) Iteration: 1 Training RMSE: 1.05354
3.90823) Iteration: 2 Training RMSE: 1.00054
5.05744) Iteration: 3 Training RMSE: 0.975234
6.35913) Iteration: 4 Training RMSE: 0.959926
7.57246) Iteration: 5 Training RMSE: 0.949503
Can you please try:
1) verify you got the latest version from mercurial and recompile.
2) delete cache files using the command "rm fR smallnetflix_mm.*"
Let me know if this works!
Thanks a lot! I deleted all the cache files and finally got correct outputs.
DeleteI run baseline of different means, results are showed as below:
ReplyDeleteUser means:
0.246803) Iteration: 0 Training RMSE: 0.9728 Validation RMSE: 0.9728
Item means:
0.240668) Iteration: 0 Training RMSE: 1.0005 Validation RMSE: 1.0005
Global means:
0.22687) Iteration: 0 Training RMSE: 1.0781 Validation RMSE: 1.0781
ALS:
I run this command
./toolkits/collaborative_filtering/als training=smallnetflix_mm validation=smallnetflix_mme lambda=0.065 minval=1 maxval=5 max_iter=6 quiet=1
Get this result:
1.0407) Iteration: 0 Training RMSE: 1.57422 Validation RMSE: 1.26173
2.15975) Iteration: 1 Training RMSE: 0.757194 Validation RMSE: 1.21038
3.27556) Iteration: 2 Training RMSE: 0.697027 Validation RMSE: 1.18852
4.39368) Iteration: 3 Training RMSE: 0.672537 Validation RMSE: 1.17485
5.51733) Iteration: 4 Training RMSE: 0.656315 Validation RMSE: 1.16683
6.67326) Iteration: 5 Training RMSE: 0.645484 Validation RMSE: 1.16204
7.79483) Iteration: 6 Training RMSE: 0.637849 Validation RMSE: 1.15905
8.92256) Iteration: 7 Training RMSE: 0.632197 Validation RMSE: 1.15763
10.0482) Iteration: 8 Training RMSE: 0.627851 Validation RMSE: 1.1572
11.1715) Iteration: 9 Training RMSE: 0.624425 Validation RMSE: 1.15746
I also tried different parameters of max_iter and D, but the results(Validation RMSE) I got from als were worse than baseline.
I don't know how this happened? Is it happened because I have not correctly use this tool?
What's the result of als algorithm on small netflix dataset? Can you show me?
Hi,
DeleteFirst of all, when using the baseline method, it seems you are using the training dataset as the validation dataset and thus you get the same training and validation RMSE.
When I run it on the validation I am getting (for global means)
$ ./toolkits/collaborative_filtering/baseline training=smallnetflix_mm validation=smallnetflix_mme quiet=1
...
1.72134) Iteration: 0 Training RMSE: 1.0781 Validation RMSE: 1.09003
Second, you are right that ALS overfits the training and have very good error of 0.624 while the validation error is even worse than the baseline. I suggest trying SGD instead :
bickson@thrust:~/graphchi$ ./toolkits/collaborative_filtering/sgd training=smallnetflix_mm validation=smallnetflix_mme quiet=1 minval=1 sgd_lambda=1e2 maxval=5 sgd_gamma=1e2 sgd_step_dec=0.9999
WARNING: common.hpp(print_copyright:139): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[validation] => [smallnetflix_mme]
[quiet] => [1]
[minval] => [1]
[sgd_lambda] => [1e2]
[maxval] => [5]
[sgd_gamma] => [1e2]
[sgd_step_dec] => [0.9999]
...
4.31135) Iteration: 0 Training RMSE: 1.01389 Validation RMSE: 1.03374
8.08941) Iteration: 1 Training RMSE: 0.94112 Validation RMSE: 1.00307
11.5534) Iteration: 2 Training RMSE: 0.926045 Validation RMSE: 0.993292
14.9594) Iteration: 3 Training RMSE: 0.917201 Validation RMSE: 0.987297
As you can see both training and validation error are better than the baseline.
I have read the codes of als algorithm.
Delete/**
* Vertex update function  computes the least square step
*/
void update(graphchi_vertex &vertex, graphchi_context &gcontext) {
vertex_data & vdata = latent_factors_inmem[vertex.id()];
mat XtX = mat::Zero(D, D);
vec Xty = vec::Zero(D);
bool compute_rmse = (vertex.num_outedges() > 0);
// Compute XtX and Xty (NOTE: unweighted)
for(int e=0; e < vertex.num_edges(); e++) {
float observation = vertex.edge(e)>get_data();
vertex_data & nbr_latent = latent_factors_inmem[vertex.edge(e)>vertex_id()];
Xty += nbr_latent.pvec * observation;
XtX.triangularView() += nbr_latent.pvec * nbr_latent.pvec.transpose();
if (compute_rmse) {
double prediction;
rmse_vec[omp_get_thread_num()] += als_predict(vdata, nbr_latent, observation, prediction);
}
}
for(int i=0; i < D; i++) XtX(i,i) += (lambda); // * vertex.num_edges();
// Solve the least squares problem with eigen using Cholesky decomposition
vdata.pvec = XtX.selfadjointView().ldlt().solve(Xty);
}
I modified the codes of lambda regulations：
for(int i=0; i < D; i++) XtX(i,i) +=(lambda)*vertex.num_edges();
It works much better.I don't know why you comment "// * vertex.num_edges();" According to the paper "Yunhong Zhou, Dennis Wilkinson, Robert Schreiber and Rong Pan. LargeScale Parallel Collaborative Filtering for the Netflix Prize." It indeed needs it.
Hi Weiwen,
DeleteThanks for your comment, I have added an additional flag called regnormal, where on default (1) it adds regularization as described by the paper by Zhou Wilkinson and Scheriber, and when set to zero, it does add lambda as regularization. This applies to the algorithms: als, sparse_als, als_tensor, pmf and wals.
Thanks a lot, It works now! I should choose different parameters to control overfitting on different datasets.
ReplyDeleteHi Danny,
ReplyDeleteThanks for your powerful toolkit!
There are two questions I hope you could help me.
The first one is about zero rating. My rating matrix is a complete one, but quite sparse with a lot of zero ratings. In this case, how can I differentiate the zero rating from nonrated ones? The zero ratings contribute for RMSE calculation and objective function minimization.
The second one is about the recommendation for a new user. In your examples, the users in the validation and test files are the same with the ones in the training files. How can I predict the rating of a new user when I have its probe rating and the trained U, V matrices?
Thanks a lot.
Best,
Rico
Most of the algorithms like SGD, ALS etc. can take into computation ratings which are zero, in that case they try to force the product of the matching user and item feature vectors to be close to zero. When a rating is not specified this useritem pair is not taken into account int he computation. So uknown ratings should be simply ignored and not entered into the input file.
DeleteAn additional approach, is in WALS algorithm, where there is a weight for each rating. In that case you can put a confidence level in the rating correctness, where rating with larger weight will influence the computation more.
The SGD, ALS algorithms are not incremental, so if a new user with known ratings is added you will need to run the algorithm again. It is possible however to store the results of the previous computation, and load it using using load_factors_from_file, that we the computation with the new user will start from the best computed previous position. Note that the new user ID will have to be in the matrix range of the previous computation (so you need to assume a bound on the number of new users).
In case there is no information at all about the new user, not much can be done, in that case you can recommend popular items for example.
Hi Danny,
ReplyDeleteThank you very much for your help.
So assume my training rating matrix is
>> A=[1 2 ; 3 0]
A =
1 2
3 0
Namely, user 1 has rated item 1 with the rating 1, item 2 with the rating 2, and user 2 has rated item 1 with the rating of 3, item 2 with the rating 0.
And for testing, I have a new user 3, who has rated item 1 with the rating 5, but his rating for item 2 is unknown.
Then my training input file should be :
%%MatrixMarket matrix coordinate real general
% Generated 1April2013
3 2 5
1 1 1
2 1 3
3 1 5
1 2 2
2 2 0
If assume we know the groundtruth of the new user 3, whose rating for item 2 is 4. So Then my validation input file should be :
%%MatrixMarket matrix coordinate real general
% Generated 1April2013
3 2 2
3 1 5
3 2 4
Are these right forms?
Thank you very much!
Best,
Rico
Hi Rico,
DeleteThe training and validation formats are fine. My only concern is that user 3 have rated item 1 in the training, and item 2 in validation, so there will be no more additional items to rate for her since there are only 2 items. Besides of that the syntax is fine.
Best,
Thank Danny!
ReplyDeleteThe reason is that I want to get the validation RMSE as my evaluation metric to compare different algorithms. That is, I view the rating in the validation file as the groundtruth, and compare the groundtruth and the prediction by the algorithm.
Best,
Hi, Danny!
ReplyDeleteDoes the ALSWR method based on Y. Koren et al. paper "Collaborative Filtering for Implicit Feedback Datasets" differ from WALS, presented here? I'm asking, because GraphChi needs two parameters, rating AND weight, while Mahout impl of ALSWR requires only confidence ratings (r_ij according to the article)? Probably I missed something, but I want to compare the results with implicit feedback and no numeric ratings (user 'watched' a TV show 5 times)
Hi,
DeleteIt is the same method, but our implementation is more general since it allows for non binary ratings. Namely rating can be reals and not just 0/1.
Hi Dr. Bickson,
ReplyDeleteI am trying to run genSGD on some of my data with 43 features. The program gives me the following error: FATAL: gensgd.cpp(main:1136): file_columns exceeds the allowed storage limit  please increase FEATURE_WIDTH and recompile.
My command is: ./toolkits/collaborative_filtering/gensgd training=GroupAGraphChi.csv val_pos=1 rehash=1 max_iter=100 gensgd_mult_dec=0.999999 minval=0 quiet=1 calc_error=1 file_columns=44
My question is, how may I increase Feature_Width? I searched this page and could not find any except for the "D" option. I tried it as follow:
./toolkits/collaborative_filtering/gensgd training=GroupAGraphChi.csv val_pos=1 rehash=1 max_iter=100 gensgd_mult_dec=0.999999 minval=0 quiet=1 calc_error=1 file_columns=44 D 50
But it still does not work. (Moreover, Latent variable width is definitely a different creature from feature width).
Any suggestion? Thank you so much!
Wendy
Hi Wendy,
DeleteThis is rather simple. You need to change line 43 of gensgd.cpp to have your new data width + 1. You can view the code here: https://code.google.com/p/graphchi/source/browse/toolkits/collaborative_filtering/gensgd.cpp
After this change you must recompile (using make clean; make cf)
Best,
Got it! Many thanks!
DeleteAlso, is there a rather conservative way to get the numbers for the Matrix Market header?
This is what I found from a quick search:
"""If format was specified as coordinate, then the size line has the form:
m n nonzeros
where
m is the number of rows in the matrix;
n is the number of columns in the matrix;
nonzeros is the number of nonzero entries in the matrix (for general symmetry), ."""
But it seems that your construction of the MM header does not follow this guideline.
Thanks again!
I am not sure I got your question: here is the explanation http://bickson.blogspot.com/2012/02/matrixmarketformat.html
DeleteYou statement is right.
Hi Danny,
ReplyDeleteI've been trying to get the climf algorithm to run but I'm having issues. I am running it on a matri market format with 629233 users and 2039744 items with 35950755 observations. Here is the MM file specification:
%%MatrixMarket matrix coordinate real general
%===============================================================================
629233 2039744 35950755
This is what I get from climf with extra configuration enabled. The machine has 40000m of free space to run this on. I've also tried running this with all of the default parameters.
worio@kona:~/collaborative_filtering/graphchi$ ./toolkits/collaborative_filtering/climf training=/home/worio/zite_likes_dataset/train.tsv max_iter=6 nshards=1 membudget_mb 40000 execthreads 8 dim=50
[training] => [/home/worio/zite_likes_dataset/train.tsv]
[max_iter] => [6]
[nshards] => [1]
[dim] => [50]
INFO: chifilenames.hpp(find_shards:258): Detected number of shards: 1
INFO: chifilenames.hpp(find_shards:259): To specify a different number of shards, use commandline parameter 'nshards'
INFO: io.hpp(convert_matrixmarket:478): File /home/worio/zite_likes_dataset/train.tsv was already preprocessed, won't do it again.
INFO: io.hpp(read_global_mean:109): Opened matrix size: 629233 x 2039744 edges: 35950755 Global mean is: 0.905809 time bins: 0 Now creating shards.
[feature_width] => [20]
[users] => [629233]
[movies] => [2039744]
[training_ratings] => [35950755]
[number_of_threads] => [8]
[membudget_Mb] => [40000]
DEBUG: stripedio.hpp(stripedio:201): Start iomanager with 2 threads.
INFO: graphchi_engine.hpp(graphchi_engine:150): Initializing graphchi_engine. This engine expects 4byte edge data.
INFO: chifilenames.hpp(load_vertex_intervals:378): shard: 0  2668975
INFO: graphchi_engine.hpp(run:673): GraphChi starting
INFO: graphchi_engine.hpp(run:674): Licensed under the Apache License 2.0
INFO: graphchi_engine.hpp(run:675): Copyright Aapo Kyrola et al., Carnegie Mellon University (2012)
DEBUG: slidingshard.hpp(sliding_shard:193): Total edge data size: 143803020, /home/worio/zite_likes_dataset/train.tsv.edata.e4B.0_1sizeof(ET): 4
INFO: graphchi_engine.hpp(print_config:125): Engine configuration:
INFO: graphchi_engine.hpp(print_config:126): exec_threads = 8
INFO: graphchi_engine.hpp(print_config:127): load_threads = 4
INFO: graphchi_engine.hpp(print_config:128): membudget_mb = 40000
INFO: graphchi_engine.hpp(print_config:129): blocksize = 4194304
INFO: graphchi_engine.hpp(print_config:130): scheduler = 0
INFO: graphchi_engine.hpp(run:706): Start iteration: 0
INFO: graphchi_engine.hpp(run:760): 0.000497s: Starting: 0  2668975
INFO: graphchi_engine.hpp(run:773): Iteration 0/5, subinterval: 0  2668975
DEBUG: memoryshard.hpp(load_edata:249): Compressed/full size: 0.0412882 number of blocks: 35
INFO: graphchi_engine.hpp(run:799): Start updates
INFO: graphchi_engine.hpp(exec_updates_inmemory_mode:450): Inmemory mode: Iteration 0 starts.
DEBUG: climf.cpp(before_iteration:59): before_iteration: resetting MRR
DEBUG: mrr_engine.hpp(reset_mrr:118): Detected number of threads: 8
Training objective:2.35614e+10
DEBUG: climf.cpp(after_iteration:77): after_iteration: running validation engine
INFO: graphchi_engine.hpp(exec_updates_inmemory_mode:450): Inmemory mode: Iteration 1 starts.
DEBUG: climf.cpp(before_iteration:59): before_iteration: resetting MRR
DEBUG: mrr_engine.hpp(reset_mrr:118): Detected number of threads: 8
FATAL: climf.hpp(dg:108): overflow in dg()
terminate called after throwing an instance of 'char const*'
Aborted (core dumped)
I haven't figured out how to get past this point and I was wondering if you could give me a few pointers on how to get this to run correctly.
Thanks!
Need to decrease step sizes (sgd_gamma) and regularization (sgd_lambda)
ReplyDeleteBest,
Hi Danny,
ReplyDeleteI am comparing accuracy of different algorithms and i need a way to get total RMSE of an algorithm, is there any command in graphchi to compute total RMSE? what about getting accuracy results in MAE?
plus i am getting segmentation fault error on MOVIELENS_MM and MOVIELENS_MME when trying to use SGD. any suggestions?
what i meant was test error RMSE.
ReplyDeleteHi Sam,
DeleteYou should prepare an additional validation file and pass it into graphchi using the command line validation=filename. The validation RMSE will be printed in each iteration.
Please send us the full error you are getting for SGD. Verify you are taking the latest version from github, and send us the full command line you used.
Best,
Thanks for your quick response, i'm new to this field so excuse my low level questions and spending your valuable time is highly appreciated in advance, i got familiar to MF and Graphchi Framework by advice of Tauqi chen:
Delete1.in ALS the max Iter is 15 no matter what you choose for maxiter, 2.regarding RMSE can we refer to Validation as the results of accuracy of our experiment?
3. what kind of visualizations(rather than RMSE charts) we could use to show results of our experiments? what tools we could use? Excel charts?
4.In ALS by adjusting lamda from 1e4 to something much bigger like 10 or 20 i get better results. is it ok? can we infer we increased accuracy by regularizing weights of parameter to a small range?
5. is there any way to tune regularization parameters for each q,p and their biases in SGD?
6. is there any reference to compare time and space complexity of Algos implemented in Graphchi/Graphlab?
7. In SGD i get best results on factor Width D=13 on Movielens 100k, we can infer that lower width is harder to distinguish reliable factors and for higher dimensions there are noise in U and V matrixes?
8.this is my problem that also happens with some other algos:
sam@sam:~/graphchi$ ./toolkits/collaborative_filtering/baseline training=smallnetflix_mm validation=smallnetflix_mm minval=1 maxval=5 quiet=1 algorithm=user_mean membudget_mmb 20000
WARNING: common.hpp(print_copyright:183): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[validation] => [smallnetflix_mm]
[minval] => [1]
[maxval] => [5]
[quiet] => [1]
[algorithm] => [user_mean]
[feature_width] => [20]
[users] => [95526]
[movies] => [3561]
[training_ratings] => [3298163]
[number_of_threads] => [4]
[membudget_Mb] => [800]
Segmentation fault (core dumped)
Best,
Sam
Hi Sam!
Delete1) are you using the latest version of graphchi from github? max_iter is a variable and should not be always 15.
2) You can use both training and validation RMSE as measures of the success of your CF method
3) This is a good question  there is no standard way. I suggest registering to our beta at: http://beta.graphlab.com to learn more about visualization and applicability of graphlab
4) It depends on the matrix and the values inside it. Probably you have big values.
5) You need to do it manually. No automated method yet.
6) There are many related papers in this domain. See the the first part of this blog opst.
7) You should try different widths and you will get different results for each dataset.
8) THere is still not enough information to debug this. Please send also your OS type. Are yo working on a virtual box under windows? Note that validation and training can not use the same file name. Verify you get the latest from github. You can compile in debug using "make clean; make cfd"
and then run:
gdb ./toolkits/collaborative_filtering/baseline
run training=smallnetflix_mm validation=smallnetflix_mm minval=1 maxval=5 quiet=1 algorithm=user_mean membudget_mmb 20000
==> send me the full output of the failure, including the output of the command "where" when it fails.
best
Hi again, I have the same situation over SVDPP, i use Ubuntu and it's installed on a cori3 Intel with 2GB Ram although i have separately installed windows:
Deletesam@sam:~/graphchi$ ./toolkits/collaborative_filtering/svdpp training=smallnetflix_mm validation=smallnetflix_mme biassgd_lambda=1e4 biassgd_gamma=1e4 minval=1 maxval=5 max_iter=6 quiet=1
WARNING: common.hpp(print_copyright:183): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[validation] => [smallnetflix_mme]
[biassgd_lambda] => [1e4]
[biassgd_gamma] => [1e4]
[minval] => [1]
[maxval] => [5]
[max_iter] => [6]
[quiet] => [1]
Segmentation fault (core dumped)
Please do the following:
Deletecompile in debug using "make clean; make cfd"
and then run:
gdb ./toolkits/collaborative_filtering/svdpp
run training=smallnetflix_mm validation=smallnetflix_mme biassgd_lambda=1e4 biassgd_gamma=1e4 minval=1 maxval=5 max_iter=6 quiet=1
==> send me the full output of the failure, including the output of the command "where" when it fails.
Dear Danny
DeleteThis is what i get, please consider that i dont have this problem with ALS and SGD but with some other commands like basline and biasSGD and SVDPP..:
sam@sam:~/graphchi$ gdb ./toolkits/collaborative_filtering/svdpp
GNU gdb (Ubuntu/Linaro 7.42012.040ubuntu2.1) 7.42012.04
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686linuxgnu".
For bug reporting instructions, please see:
...
Reading symbols from /home/sam/graphchi/toolkits/collaborative_filtering/svdpp...done.
(gdb) run training=smallnetflix_mm validation=smallnetflix_mme biassgd_lambda=1e4 biassgd_gamma=1e4 minval=1 maxval=5 max_iter=6 quiet=1
Starting program: /home/sam/graphchi/toolkits/collaborative_filtering/svdpp training=smallnetflix_mm validation=smallnetflix_mme biassgd_lambda=1e4 biassgd_gamma=1e4 minval=1 maxval=5 max_iter=6 quiet=1
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/i386linuxgnu/libthread_db.so.1".
WARNING: common.hpp(print_copyright:183): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[validation] => [smallnetflix_mme]
[biassgd_lambda] => [1e4]
[biassgd_gamma] => [1e4]
[minval] => [1]
[maxval] => [5]
[max_iter] => [6]
[quiet] => [1]
[New Thread 0xb7ca3b40 (LWP 2301)]
[New Thread 0xb74a2b40 (LWP 2302)]
[New Thread 0xb6a5cb40 (LWP 2303)]
[New Thread 0xb625bb40 (LWP 2304)]
[New Thread 0xb5a5ab40 (LWP 2305)]
[New Thread 0xb4cffb40 (LWP 2306)]
[New Thread 0xb44feb40 (LWP 2307)]
[New Thread 0xafa94b40 (LWP 2308)]
[Thread 0xafa94b40 (LWP 2308) exited]
[New Thread 0xae0bab40 (LWP 2309)]
[New Thread 0xad8b9b40 (LWP 2310)]
[New Thread 0xad0b8b40 (LWP 2311)]
[Thread 0xad8b9b40 (LWP 2310) exited]
[Thread 0xae0bab40 (LWP 2309) exited]
Program received signal SIGSEGV, Segmentation fault.
0xb7f609bc in ?? () from /usr/lib/i386linuxgnu/libstdc++.so.6
(gdb) where
#0 0xb7f609bc in ?? () from /usr/lib/i386linuxgnu/libstdc++.so.6
#1 0xb7f60a4e in std::basic_string, std::allocator >::~basic_string() () from /usr/lib/i386linuxgnu/libstdc++.so.6
#2 0x08053bdf in validation_rmse (
prediction_func=0x8054a2a , gcontext=..., tokens_per_row=3, avgprd=0x0,
pmf_burn_in=0) at rmse.hpp:206
#3 0x0805f433 in SVDPPVerticesInMemProgram::after_iteration (this=0xbffff118,
iteration=0, gcontext=...) at svdpp.cpp:154
#4 0x08072618 in graphchi::graphchi_engine >::exec_updates_inmemory_mode (this=0xbffff134,
userprogram=..., vertices=...) at ../../src/engine/graphchi_engine.hpp:481
#5 0x08067e84 in graphchi::graphchi_engine >::run (this=0xbffff134, userprogram=...,
_niters=6) at ../../src/engine/graphchi_engine.hpp:807
#6 0x080559ce in main (argc=9, argv=0xbffff334) at svdpp.cpp:302
(gdb)
Also please advise me:
Deletei used MOVIELENS 10M from your provided datasets and tried SGD and ALS and tried to tuned both Algos parameters (Assuming that Lamda is independet from gamma and matrix width) so SGD converges at Iter 96 with Validation RMSE of 0.898646 with Lamda 0.1,Gamma 0.01 and With 13 and ALS validation RMSE of 0.8589 with Lamda 10 and width 14 at itter 14.
what is the problem? i thought that SGD should give better results.
as i said i considered parameters independent for example i kept Lamda and gamma constant and checked different widths and for lmda and gamma the same, kept one constant and found best lamda and gamma.
Hi Sam,
DeleteSGD should not give better results vs. ALS  all depends on dataset properties so it is always advised to try both.
Regarding the seg fault. I can't reproduce this error  especially rmse.hpp:206 does not exist in my code. are you using the latest version from github?
i have a question that has been in my mind for quiet some time:
ReplyDeleteGraphLab and Graphchi get the data and convert it to a graph structure. while this is the main idea for graphbased social network analysis as they treat users or items or both of them as vertices and their relations as edges (in RS Handbook 2 approaches are mentioned to overcome Neighborhoodbased issues) but in Matrix factorization approaches we don't need to define any graphs.why we need to model data as graph for computing MF models?
Hi Sam,
DeleteViewing a problem as a graph is only a way of thinking about the problem and it has sometimes some benefits. There is a correspondence between graph and sparse matrix, so both ways of presentations are interchangeable.
Dear Danny
ReplyDeleteI am thankful for your wonderful support. Could you please advise me if SGD implementation in Graphchi includes the confidence Koren mentions in his paper?
in the paper you mentioned for implementation of SGD, Koren mentions a section"Input with Varying Confidence levels" and accounts for Cui as Confidence.
my guess is that this implemetation does not have confidence in it and i should use WALS.
Also i have to impute the confidence separately and there is no option that Graphchi compute it based on number of occurance, right? any advise sir?
I think there's a typo in the section "6) View the output", it says
ReplyDelete"The files store the matrices U and V in sparse matrix market format."
but it should be
"dense matrix market format"
Thanks! Typo fixed.
ReplyDeleteWill the 'rating model=ALS' compute the topN for CLiMF as well? I feel like the calculation should be the same as for the other matrix factorisation algorithms, i.e., you're still just trying to find for each row U the columns in V with the largest dot product (since sigmoid(x) is a strictly increasing function of x, the dot products correspond to the sigmoid of the predicted ranking, and we are trying to maximise this quantity).
ReplyDeleteThats a great suggestion! I have just added climf support for the rating utility. Please pull from git, recompile and let me know if it works for you. (Note that climf computes MRR estimation and not rating between 15).
DeleteIs it possible to save the model produced by these algorithms, and then apply it to new data?
ReplyDeleteYes. You can run once, and then when new data comes you can use the command line arguments load_factors_from_file=1 which will load the saved model. You will also want to use the test=filename to point to the new data you want to predict on.
DeleteHi Dr. Bickson,
ReplyDeleteI tried it as follow for trying to run PMF.
./toolkits/collaborative_filtering/pmf training=smallnetflix_mm quiet=1 minval=1 max_val=5 max_iter=10 pmf_burn_in=5
But, I got the following error after 2 iterations.
assertion "!std:isnan" failed: file "pmf.cpp", line 120, function float pmf_predict
aborted
can I know the solution?
Delete Gates
Several words have been missed out in error message.
Deleteassertion "!std:isnan(err)" failed: file "pmf.cpp", line 120, function: float pmf_predict(const vertex_data&, const vertex_data&, float, double&, void*)
aborted
It seems you got into numerical errors. Try to use the minval=XX and maxval=XX command line arguments to limit the range of predicted values. If you like to send me a small dataset where this error happens I will be happy to take a look.
DeleteThanks for your reply, heartily.
DeleteI used the netflix dataset "smallnetflix_mm" that you linked http://www.select.cs.cmu.edu/code/graphlab/datasets/smallnetflix_mm).
And I already used the minval=1 and maxval=5 command line arguments.
I haven't the vaguest idea what to do.
 Gates
Are you working on MAC OS? For me on ubuntu it works perfectly:
Delete> ./toolkits/collaborative_filtering/pmf training=smallnetflix_mm quiet=1 max_iter=10 pmf_burn_in=5
WARNING: common.hpp(print_copyright:195): GraphChi Collaborative filtering library is written by Danny Bickson (c). Send any comments or bug reports to danny.bickson@gmail.com
[training] => [smallnetflix_mm]
[quiet] => [1]
[max_iter] => [10]
[pmf_burn_in] => [5]
=== REPORT FOR sharder() ===
[Timings]
edata_flush: 0.22242s (count: 26, min: 0.001595s, max: 0.009056, avg: 0.00855462s)
execute_sharding: 0.690054 s
finish_shard.sort: 0.233932 s
preprocessing: 1.60072 s
shard_final: 0.52435 s
[Other]
app: sharder
3.56735) Iteration: 0 Training RMSE: 2.06394
4.19939) Iteration: 1 Training RMSE: 5.78686
4.82064) Iteration: 2 Training RMSE: 2.47062
5.46099) Iteration: 3 Training RMSE: 0.967806
6.0911) Iteration: 4 Training RMSE: 0.754852
Finished burnin period. starting to aggregate samples
6.71075) Iteration: 5 Training RMSE: 0.710299
7.34047) Iteration: 6 Training RMSE: 0.692969
7.96921) Iteration: 7 Training RMSE: 0.68672
8.5696) Iteration: 8 Training RMSE: 0.681699
9.20056) Iteration: 9 Training RMSE: 0.677543
Thank you very much.
DeleteIt works well on ubuntu.
I have one more question to get top k recommendations with PMF.
Doesn't the rating / ratings command support yet PMF?
Not yet. I advise giving a list of user/item pairs using the test=filename command, ratings will computed for the list.
DeleteHi Danny.
ReplyDeleteThank you so much for your support.
But I have one question.
Could you please advise me how to make its speed fast?
You said that "for speedup, verify that your program is compiled using the "O3" or EIGEN_NDEBUG compiler flag.”
I want to get more detailed information of it for executing your codes(ALS/wALS/SVD/RBM/PMF).
It would be very thankful if you respond it.
Best regards, Yuna.
I suggest verifying the macro
Delete#define GRAPHCHI_DISABLE_COMPRESSION
is defined. It should be defined at the top of the .cpp file before all the includes (for example als.cpp). Then you need to make clean and make cf.
This will give a speedup of x2.
Hi Danny.
ReplyDeleteI first ran
./toolkits/collaborative_filtering/svdpp training=smallnetflix_mm validation=smallnetflix_mme biassgd_lambda=1e4 biassgd_gamma=1e4 minval=1 maxval=5 max_iter=6 quiet=1
and then I ran
./toolkits/collaborative_filtering/rating training=smallnetflix_mm num_ratings=5 quiet=1 algorithm=als
the output said
FATAL: io.hpp(load_matrix_market_matrix:849): Wrong matrix size detected, command line argument should be D=20 instead of : 40
terminate called after throwing an instance of 'char const*'
Aborted
Can you tell me why? thanks!
The algorithm in step 2 should match the algorithm in step 1. Namely it should be algorithm=svdpp and not algorithm=als as you wrote.
Deletethanks for your help, everything goes well now. I plan to write prediction code using rbm algorithm, can you give give some materials about graphchi, for example, the documentation,etc.
DeleteHi,
DeletePer your request, I have added support for RBM top K computation. You should use the rating2 application with algorithm=rbm. See documentation above for details.
Hi Danny,
DeleteThank you very much for your support. I have run the prediction of the rbm algorithm, but it comes out that almost all of the user, the algorithm have recommend the item 1801 and 2964. I don't think it is a satisfying result.
Yes, I have noticed the same problem. It may be related to the algorithm, you can try with different parameters or running more iterations.
DeleteThank you for your advice, I will try it.
DeleteHi Danny.
ReplyDeleteI am trying to run sgd,svdpp,timesvdpp on movielens data but I can't achieve performance mentioned in "Matrix Factorization Techniques for Recommender Systems". I have tried a lot to initial parameter. For SGD I am doing ./toolkits/collaborative_filtering/sgd training=userMovielens kfold_cross_validation=10 kfold_cross_validation_index=3 sgd_lambda=0.001 sgd_gamma=0.03 minval=1 maxval=5 max_iter=600 quiet=1 sgd_step_dec=0.9 D=65. Can you please point out what am I doing wrong.
Hi Danny,
ReplyDeleteI have a beginners question, can GrapChi be used for text classification and regression? I would like to use GrapChi instead of Mahout to predict values and also classify text in categories.
Thank you!
Regards,
Robert
Hi Robert,
DeleteI recommend taking a look at GraphLab create: http://graphlab.com/products/create/index.html who will soon have regression and classification capabilities.
Thanks!
DeleteDear Danny,
ReplyDeleteIs there a way to run neighborhood recommender method in graphchi?
thanks,
xw
Hi,
DeleteIn graphchi we have item based methods. In GraphLab Create we are working on kNN methods. Once it is ready we will announce on our website.
This comment has been removed by the author.
ReplyDeleteDear Danny,
ReplyDeleteAbout rbm, what is the parameter D? how to give a value to D? what does the rbm_mult_step_dec mean? Thanks!
D is always the latent feature vector width (as in all methods).
Deletemultiplicative step decrement is how much you decrease the SGD step size. The default is 0.9, namely you multiply by 0.9 the step size after each iteration.
Thanks. In order to low RMSE for the test sets, I am tuning rbm_alpha, rbm_beta, D (not sure if it is necessary to tune D). Is there any other parameters I need to tune? Thanks.
ReplyDelete