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.. Copyright (C) 2001-2020 NLTK Project
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.. For license information, see LICENSE.TXT
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Crubadan Corpus Reader
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======================
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Crubadan is an NLTK corpus reader for ngram files provided
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by the Crubadan project. It supports several languages.
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>>> from nltk.corpus import crubadan
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>>> crubadan.langs() # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
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['abk', 'abn',..., 'zpa', 'zul']
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----------------------------------------
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Language code mapping and helper methods
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----------------------------------------
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The web crawler that generates the 3-gram frequencies works at the
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level of "writing systems" rather than languages. Writing systems
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are assigned internal 2-3 letter codes that require mapping to the
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standard ISO 639-3 codes. For more information, please refer to
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the README in nltk_data/crubadan folder after installing it.
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To translate ISO 639-3 codes to "Crubadan Code":
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>>> crubadan.iso_to_crubadan('eng')
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'en'
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>>> crubadan.iso_to_crubadan('fra')
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'fr'
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>>> crubadan.iso_to_crubadan('aaa')
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In reverse, print ISO 639-3 code if we have the Crubadan Code:
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>>> crubadan.crubadan_to_iso('en')
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'eng'
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>>> crubadan.crubadan_to_iso('fr')
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'fra'
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>>> crubadan.crubadan_to_iso('aa')
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---------------------------
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Accessing ngram frequencies
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---------------------------
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On initialization the reader will create a dictionary of every
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language supported by the Crubadan project, mapping the ISO 639-3
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language code to its corresponding ngram frequency.
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You can access individual language FreqDist and the ngrams within them as follows:
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>>> english_fd = crubadan.lang_freq('eng')
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>>> english_fd['the']
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728135
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Above accesses the FreqDist of English and returns the frequency of the ngram 'the'.
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A ngram that isn't found within the language will return 0:
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>>> english_fd['sometest']
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0
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A language that isn't supported will raise an exception:
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>>> crubadan.lang_freq('elvish')
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Traceback (most recent call last):
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...
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RuntimeError: Unsupported language.
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