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= EngTagger
English Part-of-Speech Tagger Library; a Ruby port of Lingua::EN::Tagger
=== Description
A Ruby port of Perl Lingua::EN::Tagger, a probability based, corpus-trained
tagger that assigns POS tags to English text based on a lookup dictionary and
a set of probability values. The tagger assigns appropriate tags based on
conditional probabilities--it examines the preceding tag to determine the
appropriate tag for the current word. Unknown words are classified according to
word morphology or can be set to be treated as nouns or other parts of speech.
The tagger also extracts as many nouns and noun phrases as it can, using a set
of regular expressions.
=== Features
* Assigns POS tags to English text
* Extract noun phrases from tagged text
* etc.
=== Synopsis:
require 'rubygems'
require 'engtagger'
# Create a parser object
tgr =
# Sample text
text = "Alice chased the big fat cat."
# Add part-of-speech tags to text
tagged = tgr.add_tags(text)
#=> "<nnp>Alice</nnp> <vbd>chased</vbd> <det>the</det> <jj>big</jj> <jj>fat</jj><nn>cat</nn> <pp>.</pp>"
# Get a list of all nouns and noun phrases with occurrence counts
word_list = tgr.get_words(text)
#=> {"Alice"=>1, "cat"=>1, "fat cat"=>1, "big fat cat"=>1}
# Get a readable version of the tagged text
readable = tgr.get_readable(text)
#=> "Alice/NNP chased/VBD the/DET big/JJ fat/JJ cat/NN ./PP"
# Get all nouns from a tagged output
nouns = tgr.get_nouns(tagged)
#=> {"cat"=>1, "Alice"=>1}
# Get all proper nouns
proper = tgr.get_proper_nouns(tagged)
#=> {"Alice"=>1}
# Get all noun phrases of any syntactic level
# (same as word_list but take a tagged input)
nps = tgr.get_noun_phrases(tagged)
#=> {"Alice"=>1, "cat"=>1, "fat cat"=>1, "big fat cat"=>1}
=== Tag Set
The set of POS tags used here is a modified version of the Penn Treebank tagset. Tags with non-letter characters have been redefined to work better in our data structures. Also, the "Determiner" tag (DET) has been changed from 'DT', in order to avoid confusion with the HTML tag, <DT>.
CC Conjunction, coordinating and, or
CD Adjective, cardinal number 3, fifteen
DET Determiner this, each, some
EX Pronoun, existential there there
FW Foreign words
IN Preposition / Conjunction for, of, although, that
JJ Adjective happy, bad
JJR Adjective, comparative happier, worse
JJS Adjective, superlative happiest, worst
LS Symbol, list item A, A.
MD Verb, modal can, could, 'll
NN Noun aircraft, data
NNP Noun, proper London, Michael
NNPS Noun, proper, plural Australians, Methodists
NNS Noun, plural women, books
PDT Determiner, prequalifier quite, all, half
POS Possessive 's, '
PRP Determiner, possessive second mine, yours
PRPS Determiner, possessive their, your
RB Adverb often, not, very, here
RBR Adverb, comparative faster
RBS Adverb, superlative fastest
RP Adverb, particle up, off, out
SYM Symbol *
TO Preposition to
UH Interjection oh, yes, mmm
VB Verb, infinitive take, live
VBD Verb, past tense took, lived
VBG Verb, gerund taking, living
VBN Verb, past/passive participle taken, lived
VBP Verb, base present form take, live
VBZ Verb, present 3SG -s form takes, lives
WDT Determiner, question which, whatever
WP Pronoun, question who, whoever
WPS Determiner, possessive & question whose
WRB Adverb, question when, how, however
PP Punctuation, sentence ender ., !, ?
PPC Punctuation, comma ,
PPD Punctuation, dollar sign $
PPL Punctuation, quotation mark left ``
PPR Punctuation, quotation mark right ''
PPS Punctuation, colon, semicolon, elipsis :, ..., -
LRB Punctuation, left bracket (, {, [
RRB Punctuation, right bracket ), }, ]
=== Requirements
* Ruby 1.8.6
* Hpricot[] (optional)
=== Install
(sudo) gem install engtagger
=== Author
of this Ruby library
* Yoichiro Hasebe (yohasebe [at]
of the original Perl module
* Aaron Coburn (acoburn [at]
=== Acknowledgement
This Ruby library is a direct port of Lingua::EN::Tagger available at CPAN.
The credit for the crucial part of its algorithm/design therefore goes to
Aaron Coburn, the author of the original Perl version.
=== License
This library is distributed under the GPL. Please see the LICENSE file.