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54 lines
2.3 KiB
Plaintext
54 lines
2.3 KiB
Plaintext
5 years ago
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.. Copyright (C) 2001-2019 NLTK Project
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.. For license information, see LICENSE.TXT
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===============================
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WordNet Lowest Common Hypernyms
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===============================
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Wordnet's lowest_common_hypernyms() method is based used to locate the
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lowest single hypernym that is shared by two given words:
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>>> from nltk.corpus import wordnet as wn
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>>> wn.synset('kin.n.01').lowest_common_hypernyms(wn.synset('mother.n.01'))
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[Synset('relative.n.01')]
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>>> wn.synset('policeman.n.01').lowest_common_hypernyms(wn.synset('chef.n.01'))
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[Synset('person.n.01')]
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This method generally returns a single result, but in some cases, more than one
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valid LCH is possible:
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>>> wn.synset('body.n.09').lowest_common_hypernyms(wn.synset('sidereal_day.n.01'))
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[Synset('attribute.n.02'), Synset('measure.n.02')]
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In some cases, lowest_common_hypernyms() can return one of the synsets which was
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passed to it as an argument:
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>>> wn.synset('woman.n.01').lowest_common_hypernyms(wn.synset('girlfriend.n.02'))
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[Synset('woman.n.01')]
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In NLTK 3.0a2 the behavior of lowest_common_hypernyms() was changed to give more
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accurate results in a small set of cases, generally when dealing with nouns describing
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social roles or jobs. To emulate the pre v3.0a2 behavior, you can set the use_min_depth=True
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flag:
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>>> wn.synset('policeman.n.01').lowest_common_hypernyms(wn.synset('chef.n.01'))
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[Synset('person.n.01')]
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>>> wn.synset('policeman.n.01').lowest_common_hypernyms(wn.synset('chef.n.01'), use_min_depth=True)
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[Synset('organism.n.01')]
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In some cases use_min_depth=True may return more or fewer results than the default
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behavior:
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>>> wn.synset('woman.n.01').lowest_common_hypernyms(wn.synset('girlfriend.n.02'))
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[Synset('woman.n.01')]
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>>> wn.synset('woman.n.01').lowest_common_hypernyms(wn.synset('girlfriend.n.02'), use_min_depth=True)
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[Synset('organism.n.01'), Synset('woman.n.01')]
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In the general case, however, they tend to return the same results:
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>>> wn.synset('body.n.09').lowest_common_hypernyms(wn.synset('sidereal_day.n.01'))
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[Synset('attribute.n.02'), Synset('measure.n.02')]
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>>> wn.synset('body.n.09').lowest_common_hypernyms(wn.synset('sidereal_day.n.01'), use_min_depth=True)
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[Synset('attribute.n.02'), Synset('measure.n.02')]
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