nltk.metrics.association.TrigramAssocMeasures

class documentation

class TrigramAssocMeasures(NgramAssocMeasures): (source)

A collection of trigram association measures. Each association measure is provided as a function with four arguments:

trigram_score_fn(n_iii,
                 (n_iix, n_ixi, n_xii),
                 (n_ixx, n_xix, n_xxi),
                 n_xxx)

The arguments constitute the marginals of a contingency table, counting the occurrences of particular events in a corpus. The letter i in the suffix refers to the appearance of the word in question, while x indicates the appearance of any word. Thus, for example: n_iii counts (w1, w2, w3), i.e. the trigram being scored n_ixx counts (w1, , *) n_xxx counts (, *, *), i.e. any trigram

Static Method	`_contingency`	Calculates values of a trigram contingency table (or cube) from marginal values. >>> TrigramAssocMeasures._contingency(1, (1, 1, 1), (1, 73, 1), 2000) (1, 0, 0, 0, 0, 72, 0, 1927)
Static Method	`_marginals`	Calculates values of contingency table marginals from its values. >>> TrigramAssocMeasures._marginals(1, 0, 0, 0, 0, 72, 0, 1927) (1, (1, 1, 1), (1, 73, 1), 2000)
Class Variable	`_n`	Undocumented

Inherited from NgramAssocMeasures:

Class Method	`chi_sq`	Scores ngrams using Pearson's chi-square as in Manning and Schutze 5.3.3.
Class Method	`jaccard`	Scores ngrams using the Jaccard index.
Class Method	`likelihood_ratio`	Scores ngrams using likelihood ratios as in Manning and Schutze 5.3.4.
Class Method	`pmi`	Scores ngrams by pointwise mutual information, as in Manning and Schutze 5.4.
Class Method	`poisson_stirling`	Scores ngrams using the Poisson-Stirling measure.
Class Method	`student_t`	Scores ngrams using Student's t test with independence hypothesis for unigrams, as in Manning and Schutze 5.3.1.
Static Method	`mi_like`	Scores ngrams using a variant of mutual information. The keyword argument power sets an exponent (default 3) for the numerator. No logarithm of the result is calculated.
Static Method	`raw_freq`	Scores ngrams by their frequency
Class Method	`_expected_values`	Calculates expected values for a contingency table.

@staticmethod
def _contingency(n_iii, n_iix_tuple, n_ixx_tuple, n_xxx): (source) ¶

overrides nltk.metrics.association.NgramAssocMeasures._contingency

Calculates values of a trigram contingency table (or cube) from marginal values. >>> TrigramAssocMeasures._contingency(1, (1, 1, 1), (1, 73, 1), 2000) (1, 0, 0, 0, 0, 72, 0, 1927)

@staticmethod
def _marginals(*contingency): (source) ¶

overrides nltk.metrics.association.NgramAssocMeasures._marginals

Calculates values of contingency table marginals from its values. >>> TrigramAssocMeasures._marginals(1, 0, 0, 0, 0, 72, 0, 1927) (1, (1, 1, 1), (1, 73, 1), 2000)

_n: int = (source) ¶

overrides nltk.metrics.association.NgramAssocMeasures._n

Undocumented