'Calculate approximate log-likelihood as score.
Parameters
X : array-like or sparse matrix, shape=(n_samples, n_features)
Document word matrix.
Returns
score : float
Use approximate bound as score.'

def score(self, X, y=None):

    X = self._check_non_neg_array(X, 'LatentDirichletAllocation.score')
    doc_topic_distr = self._unnormalized_transform(X)
    score = self._approx_bound(X, doc_topic_distr, sub_sampling=False)
    return score
