Collaborative Filtering

>>> from mlpack import cf

This program performs collaborative filtering (CF) on the given dataset. Given a list of user, item and preferences (the 'training' parameter), the program will perform a matrix decomposition and then can perform a series of actions related to collaborative filtering. Alternately, the program can load an existing saved CF model with the 'input_model' parameter and then use that model to provide recommendations or predict values.

The input matrix should be a 3-dimensional matrix of ratings, where the first dimension is the user, the second dimension is the item, and the third dimension is that user's rating of that item. Both the users and items should be numeric indices, not names. The indices are assumed to start from 0.

A set of query users for which recommendations can be generated may be specified with the 'query' parameter; alternately, recommendations may be generated for every user in the dataset by specifying the 'all_user_recommendations' parameter. In addition, the number of recommendations per user to generate can be specified with the 'recommendations' parameter, and the number of similar users (the size of the neighborhood) to be considered when generating recommendations can be specified with the 'neighborhood' parameter.

For performing the matrix decomposition, the following optimization algorithms can be specified via the 'algorithm' parameter:

- 'RegSVD' -- Regularized SVD using a SGD optimizer

- 'NMF' -- Non-negative matrix factorization with alternating least squares update rules

- 'BatchSVD' -- SVD batch learning

- 'SVDIncompleteIncremental' -- SVD incomplete incremental learning

- 'SVDCompleteIncremental' -- SVD complete incremental learning

A trained model may be saved to with the 'output_model' output parameter.

To train a CF model on a dataset 'training_set' using NMF for decomposition and saving the trained model to 'model', one could call:

>>> cf(training=training_set, algorithm='NMF')
>>> model = output['output_model']

Then, to use this model to generate recommendations for the list of users in the query set 'users', storing 5 recommendations in 'recommendations', one could call

>>> cf(input_model=model, query=users, recommendations=5)
>>> recommendations = output['output']

input options

output options

The return value from the binding is a dict containing the following elements: