recpack.algorithms.TARSItemKNNLiu2012
- class recpack.algorithms.TARSItemKNNLiu2012(K: int = 200, decay: float = 2.0)
Time aware variant of ItemKNN which uses a logarithmic decay function.
Algorithm as described in Y. Liu, Z. Xu, B. Shi and B. Zhang, “Time-Based K-nearest Neighbor Collaborative Filtering,” 2012 IEEE 12th International Conference on Computer and Information Technology, Chengdu, China, 2012, pp. 1061-1065, doi: 10.1109/CIT.2012.217.
Weights are computed based on their position in a user’s history. The first item visited by a user gets value 1, last item visited gets value 2. The decay follows a logarithmic function:
\[\Gamma(x) = \log_\alpha ((\alpha-1)x + 1) + 1\]where \(\alpha\) is the decay scaling parameter, and x is the time between the maximal timestamp in the matrix and the timestamp of the event.
- Parameters
K (int) – How many neigbours to use per item, make sure to pick a value below the number of columns of the matrix to fit on. Defaults to 200
decay (float) – The parameter of the logarithmic decay function. Defaults to 2.
Methods
fit
(X)Fit the model to the input interaction matrix.
get_params
([deep])Get parameters for this estimator.
predict
(X)Predicts scores, given the interactions in X
set_params
(**params)Set the parameters of the estimator.
Attributes
DECAY_FUNCTIONS
SUPPORTED_SIMILARITIES
Name of the object.
Name of the object's class.
- fit(X: Union[recpack.matrix.interaction_matrix.InteractionMatrix, scipy.sparse._csr.csr_matrix]) recpack.algorithms.base.Algorithm
Fit the model to the input interaction matrix.
After fitting the model will be ready to use for prediction.
This function will handle some generic bookkeeping for each of the child classes,
The fit function gets timed, and this will get printed
Input data is converted to expected type using call to
_transform_predict_input()
The model is trained using the
_fit()
method_check_fit_complete()
is called to check fitting was succesful
- Parameters
X (Matrix) – The interactions to fit the model on.
- Returns
self, fitted algorithm
- Return type
- get_params(deep=True)
Get parameters for this estimator.
- Parameters
deep (bool, default=True) – If True, will return the parameters for this estimator and contained subobjects that are estimators.
- Returns
params – Parameter names mapped to their values.
- Return type
dict
- property identifier
Name of the object.
Name is made by combining the class name with the parameters passed at construction time.
Constructed by recreating the initialisation call. Example:
Algorithm(param_1=value)
- property name
Name of the object’s class.
- predict(X: Union[recpack.matrix.interaction_matrix.InteractionMatrix, scipy.sparse._csr.csr_matrix]) scipy.sparse._csr.csr_matrix
Predicts scores, given the interactions in X
Recommends items for each nonzero user in the X matrix.
This function is a wrapper around the
_predict()
method, and performs checks on in- and output data to guarantee proper computation.Checks that model is fitted correctly
checks the output using
_check_prediction()
function
- Parameters
X (Matrix) – interactions to predict from.
- Returns
The recommendation scores in a sparse matrix format.
- Return type
csr_matrix
- set_params(**params)
Set the parameters of the estimator.
- Parameters
params (dict) – Estimator parameters