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78 lines
4.9 KiB
ReStructuredText
78 lines
4.9 KiB
ReStructuredText
Lexeme Features
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===============
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A lexeme is an entry in the lexicon --- the vocabulary --- for a word, punctuation
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symbol, whitespace unit, etc. Lexemes come with lots of pre-computed information,
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that help you write good feature functions. Features are integer-valued where
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possible --- instead of strings, spaCy refers to strings by consecutive ID numbers,
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which you can use to look up the string values if necessary.
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String features
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---------------
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+---------+-------------------------------------------------------------------+
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| SIC | The word as it appeared in the sentence, unaltered. |
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+---------+-------------------------------------------------------------------+
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| NORM | For frequent words, case normalization is applied. |
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| | Otherwise, back-off to SHAPE. |
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+---------+-------------------------------------------------------------------+
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| SHAPE | Remap the characters of the word as follows: |
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| | |
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| | a-z --> x, A-Z --> X, 0-9 --> d, ,.;:"'?!$- --> self, other --> \*|
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| | |
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| | Trim sequences of length 3+ to 3, e.g |
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| | |
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| | apples --> xxx, Apples --> Xxxx, app9LES@ --> xxx9XXX* |
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+---------+-------------------------------------------------------------------+
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| ASCIIED | Use unidecode.unidecode(sic) to approximate the word using the |
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| | ascii characters. |
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+---------+-------------------------------------------------------------------+
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| PREFIX | sic_unicode_string[:1] |
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+---------+-------------------------------------------------------------------+
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| SUFFIX | sic_unicode_string[-3:] |
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+---------+-------------------------------------------------------------------+
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Integer features
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----------------
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+--------------+--------------------------------------------------------------+
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| LENGTH | Length of the string, in unicode |
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+--------------+--------------------------------------------------------------+
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| CLUSTER | Brown cluster |
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+--------------+--------------------------------------------------------------+
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| POS_TYPE | K-means cluster of word's tag affinities |
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+--------------+--------------------------------------------------------------+
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| SENSE_TYPE | K-means cluster of word's sense affinities |
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+--------------+--------------------------------------------------------------+
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Boolean features
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----------------
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+-------------+--------------------------------------------------------------+
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| IS_ALPHA | The result of sic.isalpha() |
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+-------------+--------------------------------------------------------------+
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| IS_ASCII | Check whether all the word's characters are ascii characters |
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+-------------+--------------------------------------------------------------+
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| IS_DIGIT | The result of sic.isdigit() |
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+-------------+--------------------------------------------------------------+
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| IS_LOWER | The result of sic.islower() |
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+-------------+--------------------------------------------------------------+
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| IS_PUNCT | Check whether all characters are in the class TODO |
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+-------------+--------------------------------------------------------------+
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| IS_SPACE | The result of sic.isspace() |
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+-------------+--------------------------------------------------------------+
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| IS_TITLE | The result of sic.istitle() |
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+-------------+--------------------------------------------------------------+
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| IS_UPPER | The result of sic.isupper() |
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+-------------+--------------------------------------------------------------+
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| LIKE_URL | Check whether the string looks like it could be a URL. Aims |
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| | for low false negative rate. |
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+-------------+--------------------------------------------------------------+
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| LIKE_NUMBER | Check whether the string looks like it could be a numeric |
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| | entity, e.g. 10,000 10th .10 . Skews for low false negative |
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| | rate. |
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+-------------+--------------------------------------------------------------+
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| IN_LIST | Facility for loading arbitrary run-time word lists? |
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+-------------+--------------------------------------------------------------+
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