conditional_random_field_test.py 文件源码

def test_forward_works_without_mask(self):
        log_likelihood = self.crf(self.logits, self.tags).data[0]

        # Now compute the log-likelihood manually
        manual_log_likelihood = 0.0

        # For each instance, manually compute the numerator
        # (which is just the score for the logits and actual tags)
        # and the denominator
        # (which is the log-sum-exp of the scores for the logits across all possible tags)
        for logits_i, tags_i in zip(self.logits, self.tags):
            numerator = self.score(logits_i.data, tags_i.data)
            all_scores = [self.score(logits_i.data, tags_j) for tags_j in itertools.product(range(5), repeat=3)]
            denominator = math.log(sum(math.exp(score) for score in all_scores))
            # And include them in the manual calculation.
            manual_log_likelihood += numerator - denominator

        # The manually computed log likelihood should equal the result of crf.forward.
        assert manual_log_likelihood == approx(log_likelihood)