Class: UEAStemmer

Inherits:
Object
  • Object
show all
Includes:
StringHelpers
Defined in:
lib/word.rb,
lib/rule.rb,
lib/uea-stemmer.rb

Overview

Copyright 2005 University of East Anglia

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

Authored by Marie-Claire Jenkins and Dr. Dan J. Smith. Ported to Java from Perl by Richard Churchill. Ported from Java to Ruby by Jason M. Adams.

Direct Known Subclasses

DefaultUEAStemmer

Defined Under Namespace

Classes: ConcatenatingEndingRule, CustomRule, EndingRule, NonExhaustiveEndingRule, Rule, Word

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from StringHelpers

#ends_with?, #remove_suffix

Constructor Details

#initialize(max_word_length = nil, max_acronym_length = nil) ⇒ UEAStemmer

Returns a new instance of UEAStemmer.



32
33
34
35
36
37
38
 
# File 'lib/uea-stemmer.rb', line 32

def initialize(max_word_length = nil, max_acronym_length = nil)
  @max_word_length = max_word_length || 'deoxyribonucleicacid'.size
  @max_acronym_length = max_acronym_length || 'CAVASSOO'.size

  @rules = Array.new
  create_rules
end

Instance Attribute Details

#max_acronym_length ⇒ Object

Returns the value of attribute max_acronym_length.



29
30
31
 
# File 'lib/uea-stemmer.rb', line 29

def max_acronym_length
  @max_acronym_length
end

#max_word_length ⇒ Object

Returns the value of attribute max_word_length.



29
30
31
 
# File 'lib/uea-stemmer.rb', line 29

def max_word_length
  @max_word_length
end

#rules ⇒ Object (readonly)

Returns the value of attribute rules.



30
31
32
 
# File 'lib/uea-stemmer.rb', line 30

def rules
  @rules
end

Instance Method Details

#add_rule(rule) ⇒ Object 



77
78
79
80
81
82
83
84
 
# File 'lib/uea-stemmer.rb', line 77

def add_rule(rule)
  if rule.kind_of?(Rule)
    @rules << rule.dup.freeze
    true
  else
    false
  end
end

#num_rules ⇒ Object 



73
74
75
 
# File 'lib/uea-stemmer.rb', line 73

def num_rules
  @rules.map { |r| r.rule_num }.uniq.size + 4    # four rules not covered by the rules array
end

#stem(word) ⇒ Object 



69
70
71
 
# File 'lib/uea-stemmer.rb', line 69

def stem(word)
  stem_with_rule(word).word
end

#stem_with_rule(word) ⇒ Object 



40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
 
# File 'lib/uea-stemmer.rb', line 40

def stem_with_rule(word)
  stemmed_word = word.dup;
  ruleno = 0;

  if problem_word?(word)
    Word.new(word, 94)
  elsif (word.size > @max_acronym_length && word =~ /^[A-Z]+$/) || (word.size > (@max_acronym_length + 1) && word =~ /^[A-Z]+s$/)
    Word.new(word, 96)      # added by JMA to catch long acronyms
  elsif word.size > @max_word_length
    Word.new(word, 95)
  elsif word.index("'")
    if word =~ /^.*'[s]$/i
      stemmed_word = remove_suffix(stemmed_word, 2)
    elsif word =~ /^.*'$/
      stemmed_word = remove_suffix(stemmed_word, 1)
    end

    stemmed_word.gsub!(/n't/, ' not')
    stemmed_word.gsub!(/'ve/, ' have')
    stemmed_word.gsub!(/'re/, ' are')
    stemmed_word.gsub!(/'m/, ' am')

    Word.new(stemmed_word, 93)
  else
    stemmed_word, rule_num, rule = apply_rules(stemmed_word)
    Word.new(stemmed_word, rule_num, rule)
  end
end