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136 lines
4.2 KiB
Python
136 lines
4.2 KiB
Python
# -*- coding: utf-8 -*-
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# Natural Language Toolkit: Language Model Unit Tests
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#
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# Copyright (C) 2001-2019 NLTK Project
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# Author: Ilia Kurenkov <ilia.kurenkov@gmail.com>
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# URL: <http://nltk.org/>
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# For license information, see LICENSE.TXT
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import unittest
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import six
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from nltk import FreqDist
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from nltk.lm import NgramCounter
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from nltk.util import everygrams
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class NgramCounterTests(unittest.TestCase):
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"""Tests for NgramCounter that only involve lookup, no modification."""
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@classmethod
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def setUpClass(cls):
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text = [list("abcd"), list("egdbe")]
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cls.trigram_counter = NgramCounter(
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(everygrams(sent, max_len=3) for sent in text)
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)
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cls.bigram_counter = NgramCounter(
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(everygrams(sent, max_len=2) for sent in text)
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)
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def test_N(self):
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self.assertEqual(self.bigram_counter.N(), 16)
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self.assertEqual(self.trigram_counter.N(), 21)
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def test_counter_len_changes_with_lookup(self):
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self.assertEqual(len(self.bigram_counter), 2)
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_ = self.bigram_counter[50]
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self.assertEqual(len(self.bigram_counter), 3)
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def test_ngram_order_access_unigrams(self):
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self.assertEqual(self.bigram_counter[1], self.bigram_counter.unigrams)
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def test_ngram_conditional_freqdist(self):
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expected_trigram_contexts = [
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("a", "b"),
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("b", "c"),
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("e", "g"),
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("g", "d"),
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("d", "b"),
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]
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expected_bigram_contexts = [("a",), ("b",), ("d",), ("e",), ("c",), ("g",)]
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bigrams = self.trigram_counter[2]
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trigrams = self.trigram_counter[3]
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six.assertCountEqual(self, expected_bigram_contexts, bigrams.conditions())
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six.assertCountEqual(self, expected_trigram_contexts, trigrams.conditions())
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def test_bigram_counts_seen_ngrams(self):
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b_given_a_count = 1
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unk_given_b_count = 1
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self.assertEqual(b_given_a_count, self.bigram_counter[["a"]]["b"])
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self.assertEqual(unk_given_b_count, self.bigram_counter[["b"]]["c"])
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def test_bigram_counts_unseen_ngrams(self):
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z_given_b_count = 0
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self.assertEqual(z_given_b_count, self.bigram_counter[["b"]]["z"])
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def test_unigram_counts_seen_words(self):
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expected_count_b = 2
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self.assertEqual(expected_count_b, self.bigram_counter["b"])
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def test_unigram_counts_completely_unseen_words(self):
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unseen_count = 0
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self.assertEqual(unseen_count, self.bigram_counter["z"])
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class NgramCounterTrainingTests(unittest.TestCase):
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def setUp(self):
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self.counter = NgramCounter()
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def test_empty_string(self):
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test = NgramCounter("")
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self.assertNotIn(2, test)
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self.assertEqual(test[1], FreqDist())
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def test_empty_list(self):
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test = NgramCounter([])
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self.assertNotIn(2, test)
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self.assertEqual(test[1], FreqDist())
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def test_None(self):
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test = NgramCounter(None)
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self.assertNotIn(2, test)
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self.assertEqual(test[1], FreqDist())
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def test_train_on_unigrams(self):
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words = list("abcd")
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counter = NgramCounter([[(w,) for w in words]])
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self.assertFalse(bool(counter[3]))
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self.assertFalse(bool(counter[2]))
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six.assertCountEqual(self, words, counter[1].keys())
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def test_train_on_illegal_sentences(self):
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str_sent = ["Check", "this", "out", "!"]
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list_sent = [["Check", "this"], ["this", "out"], ["out", "!"]]
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with self.assertRaises(TypeError):
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NgramCounter([str_sent])
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with self.assertRaises(TypeError):
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NgramCounter([list_sent])
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def test_train_on_bigrams(self):
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bigram_sent = [("a", "b"), ("c", "d")]
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counter = NgramCounter([bigram_sent])
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self.assertFalse(bool(counter[3]))
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def test_train_on_mix(self):
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mixed_sent = [("a", "b"), ("c", "d"), ("e", "f", "g"), ("h",)]
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counter = NgramCounter([mixed_sent])
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unigrams = ["h"]
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bigram_contexts = [("a",), ("c",)]
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trigram_contexts = [("e", "f")]
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six.assertCountEqual(self, unigrams, counter[1].keys())
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six.assertCountEqual(self, bigram_contexts, counter[2].keys())
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six.assertCountEqual(self, trigram_contexts, counter[3].keys())
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