LinearFlow | R Documentation |
Creates Linear-FLow model described in Practical Linear Models for Large-Scale One-Class Collaborative Filtering. The goal is to find item-item (or user-user) similarity matrix which is low-rank and has small Frobenius norm. Such double regularization allows to better control the generalization error of the model. Idea of the method is somewhat similar to Sparse Linear Methods(SLIM) but scales to large datasets much better.
rsparse::MatrixFactorizationRecommender
-> LinearFlow
v
right singular vector of the user-item matrix. Size is n_items * rank
.
In the paper this matrix is called v
new()
creates Linear-FLow model with rank
latent factors.
LinearFlow$new( rank = 8L, lambda = 0, init = NULL, preprocess = identity, solve_right_singular_vectors = c("soft_impute", "svd") )
rank
size of the latent dimension
lambda
regularization parameter
init
initialization of the orthogonal basis.
preprocess
identity()
by default. User spectified function which will
be applied to user-item interaction matrix before running matrix factorization
(also applied during inference time before making predictions).
For example we may want to normalize each row of user-item matrix to have 1 norm.
Or apply log1p()
to discount large counts.
solve_right_singular_vectors
type of the solver for initialization of the orthogonal basis. Original paper uses SVD. See paper for details.
fit_transform()
performs matrix factorization
LinearFlow$fit_transform(x, ...)
x
input matrix
...
not used at the moment
transform()
calculates user embeddings for the new input
LinearFlow$transform(x, ...)
x
input matrix
...
not used at the moment
cross_validate_lambda()
performs fast tuning of the parameter 'lambda' with warm re-starts
LinearFlow$cross_validate_lambda( x, x_train, x_test, lambda = "auto@10", metric = "map@10", not_recommend = x_train, ... )
x
input user-item interactions matrix. Model performs matrix facrtorization based only on this matrix
x_train
user-item interactions matrix. Model recommends items based on this matrix. Usually should be different from 'x' to avoid overfitting
x_test
target user-item interactions. Model will evaluate predictions against this matrix, 'x_test' should be treated as future interactions.
lambda
numeric vector - sequaence of regularization parameters. Supports special value like 'auto@10'. This will automatically fine a sequence of lambda of length 10. This is recommended way to check for 'lambda'.
metric
a metric against which model will be evaluated for top-k recommendations.
Currently only map@k
and ndcg@k
are supported (k
can be any integer)
not_recommend
matrix same shape as 'x_train'. Specifies which items to not recommend for each user.
...
not used at the moment
clone()
The objects of this class are cloneable with this method.
LinearFlow$clone(deep = FALSE)
deep
Whether to make a deep clone.
data("movielens100k")
train = movielens100k[1:900, ]
cv = movielens100k[901:nrow(movielens100k), ]
model = LinearFlow$new(
rank = 10, lambda = 0,
solve_right_singular_vectors = "svd"
)
user_emb = model$fit_transform(train)
preds = model$predict(cv, k = 10)
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