Source code for cornac.models.hpf.recom_hpf

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import numpy as np
import scipy.sparse as sp

from cornac.models.hpf import hpf
from ..recommender import Recommender
from ...exception import ScoreException



# HierarchicalPoissonFactorization: Hpf
[docs]class HPF(Recommender): """Hierarchical Poisson Factorization. Parameters ---------- k: int, optional, default: 5 The dimension of the latent factors. max_iter: int, optional, default: 100 Maximum number of iterations. name: string, optional, default: 'HPF' The name of the recommender model. trainable: boolean, optional, default: True When False, the model is not trained and Cornac assumes that the model is already \ pre-trained (Theta and Beta are not None). verbose: boolean, optional, default: False When True, some running logs are displayed. hierarchical: boolean, optional, default: True When False, PF is used instead of HPF. init_params: dictionary, optional, default: {'G_s':None, 'G_r':None, 'L_s':None, 'L_r':None} List of initial parameters, e.g., init_params = {'G_s':G_s, 'G_r':G_r, 'L_s':L_s, 'L_r':L_r}, \ where G_s and G_r are of type csc_matrix or np.array with the same shape as Theta, see below). \ They represent respectively the "shape" and "rate" parameters of Gamma distribution over \ Theta. Similarly, L_s, L_r are the shape and rate parameters of the Gamma over Beta. Theta: csc_matrix, shape (n_users,k) The expected user latent factors. Beta: csc_matrix, shape (n_items,k) The expected item latent factors. References ---------- * Gopalan, Prem, Jake M. Hofman, and David M. Blei. Scalable Recommendation with \ Hierarchical Poisson Factorization. In UAI, pp. 326-335. 2015. """ def __init__(self, k=5, max_iter=100, name="HPF", trainable=True, verbose=False, hierarchical = True, init_params={'G_s': None, 'G_r': None, 'L_s': None, 'L_r': None}): Recommender.__init__(self, name=name, trainable=trainable, verbose = verbose) self.k = k self.init_params = init_params self.max_iter = max_iter self.ll = np.full(max_iter, 0) self.etp_r = np.full(max_iter, 0) self.etp_c = np.full(max_iter, 0) self.eps = 0.000000001 self.hierarchical = hierarchical self.Theta = None # matrix of user factors self.Beta = None # matrix of item factors # fit the recommender model to the traning data
[docs] def fit(self, train_set): """Fit the model to observations. Parameters ---------- train_set: object of type TrainSet, required An object contraining the user-item preference in csr scipy sparse format,\ as well as some useful attributes such as mappings to the original user/item ids.\ Please refer to the class TrainSet in the "data" module for details. """ Recommender.fit(self, train_set) X = sp.csc_matrix(self.train_set.matrix) # recover the striplet sparse format from csc sparse matrix X (needed to feed c++) (rid, cid, val) = sp.find(X) val = np.array(val, dtype='float32') rid = np.array(rid, dtype='int32') cid = np.array(cid, dtype='int32') tX = np.concatenate((np.concatenate(([rid], [cid]), axis=0).T, val.reshape((len(val), 1))), axis=1) del rid, cid, val if self.trainable: if self.hierarchical: res = hpf.hpf(tX, X.shape[0], X.shape[1], self.k, self.max_iter, self.init_params) else: res = hpf.pf(tX, X.shape[0], X.shape[1], self.k, self.max_iter, self.init_params) self.Theta = np.asarray(res['Z']) self.Beta = np.asarray(res['W']) elif self.verbose: print('%s is trained already (trainable = False)' % (self.name))
[docs] def score(self, user_id, item_id=None): """Predict the scores/ratings of a user for an item. Parameters ---------- user_id: int, required The index of the user for whom to perform score prediction. item_id: int, optional, default: None The index of the item for that to perform score prediction. If None, scores for all known items will be returned. Returns ------- res : A scalar or a Numpy array Relative scores that the user gives to the item or to all known items """ if item_id is None: if self.train_set.is_unk_user(user_id): u_representation = np.ones(self.k) else: u_representation = self.Theta[user_id, :] known_item_scores = self.Beta.dot(u_representation) known_item_scores = np.array(known_item_scores, dtype='float64').flatten() return known_item_scores else: if self.train_set.is_unk_user(user_id) or self.train_set.is_unk_item(item_id): raise ScoreException("Can't make score prediction for (user_id=%d, item_id=%d)" % (user_id, item_id)) user_pred = self.Beta[item_id,:].dot(self.Theta[user_id, :]) user_pred = np.array(user_pred, dtype='float64').flatten()[0] return user_pred