Source Code for Module nltk.tag.simplify

  1  # Natural Language Toolkit: POS Tag Simplification 
  2  # 
  3  # Copyright (C) 2001-2011 NLTK Project 
  4  # Author: Steven Bird <sb@csse.unimelb.edu.au> 
  5  # URL: <http://www.nltk.org/> 
  6  # For license information, see LICENSE.TXT 
  7   
  8   
  9  ###################################################################### 
 10  #{ Brown 
 11  ###################################################################### 
 12   
 13  # http://khnt.hit.uib.no/icame/manuals/brown/INDEX.HTM 
 14   
 15  brown_mapping1 = { 
 16      'j': 'ADJ', 'p': 'PRO', 'm': 'MOD', 'q': 'DET', 
 17      'w': 'WH', 'r': 'ADV', 'i': 'P', 
 18      'u': 'UH', 'e': 'EX', 'o': 'NUM', 'b': 'V', 
 19      'h': 'V', 'f': 'FW', 'a': 'DET', 't': 'TO', 
 20      'cc': 'CNJ', 'cs': 'CNJ', 'cd': 'NUM', 
 21      'do': 'V', 'dt': 'DET', 
 22      'nn': 'N', 'nr': 'N', 'np': 'NP', 'nc': 'N' 
 23      } 
 24  brown_mapping2 = { 
 25      'vb': 'V', 'vbd': 'VD', 'vbg': 'VG', 'vbn': 'VN' 
 26      } 
 27   
 28 -def simplify_brown_tag(tag): 
 29      tag = tag.lower() 
 30      if tag[0] in brown_mapping1: 
 31          return brown_mapping1[tag[0]] 
 32      elif tag[:2] in brown_mapping1:   # still doesn't handle DOD tag correctly 
 33          return brown_mapping1[tag[:2]] 
 34      try: 
 35          if '-' in tag: 
 36              tag = tag.split('-')[0] 
 37          return brown_mapping2[tag] 
 38      except KeyError: 
 39          return tag.upper() 
 40   
 41  ###################################################################### 
 42  #{ Wall Street Journal tags (Penn Treebank) 
 43  ###################################################################### 
 44   
 45  wsj_mapping = { 
 46      '-lrb-': '(',   '-rrb-': ')',    '-lsb-': '(', 
 47      '-rsb-': ')',   '-lcb-': '(',    '-rcb-': ')', 
 48      '-none-': '',   'cc': 'CNJ',     'cd': 'NUM', 
 49      'dt': 'DET',    'ex': 'EX',      'fw': 'FW', # existential "there", foreign word 
 50      'in': 'P',      'jj': 'ADJ',     'jjr': 'ADJ', 
 51      'jjs': 'ADJ',   'ls': 'L',       'md': 'MOD',  # list item marker 
 52      'nn': 'N',      'nnp': 'NP',     'nnps': 'NP', 
 53      'nns': 'N',     'pdt': 'DET',    'pos': '', 
 54      'prp': 'PRO',   'prp$': 'PRO',   'rb': 'ADV', 
 55      'rbr': 'ADV',   'rbs': 'ADV',    'rp': 'PRO', 
 56      'sym': 'S',     'to': 'TO',      'uh': 'UH', 
 57      'vb': 'V',      'vbd': 'VD',     'vbg': 'VG', 
 58      'vbn': 'VN',    'vbp': 'V',      'vbz': 'V', 
 59      'wdt': 'WH',    'wp': 'WH',      'wp$': 'WH', 
 60      'wrb': 'WH', 
 61      'bes': 'V',     'hvs': 'V',     'prp^vbp': 'PRO'   # additions for NPS Chat corpus 
 62      } 
 63   
 64 -def simplify_wsj_tag(tag): 
 65      if tag and tag[0] == '^': 
 66          tag = tag[1:] 
 67      try: 
 68          tag = wsj_mapping[tag.lower()] 
 69      except KeyError: 
 70          pass 
 71      return tag.upper() 
 72   
 73  indian_mapping = { 
 74      'nn': 'N', 'vm': 'MOD', 'jj': 'ADJ', 'nnp': 'NP', 
 75      'prp': 'PRO', 'prep': 'PRE', 'vaux': 'V', 'vfm': 'V', 
 76      'cc': 'CNJ', 'nnpc': 'NP', 'nnc': 'N', 'qc': 'QC', 
 77      'dem': 'DET', 'vrb': 'V', 'qfnum': 'NUM', 'rb': 'ADV', 
 78      'qf': 'DET', 'punc': '.', 'rp': 'PRT', 'psp': 'PSP', 
 79      'nst': 'N', 'nvb': 'N', 'vjj': 'V', 'neg': 'NEG', 
 80      'vnn': 'V', 'xc': 'XC', 'intf': 'INTF', 'nloc': 'N', 
 81      'jvb': 'ADJ', 'wq': 'WH', 'qw': 'WH', 'jj:?': 'ADJ', 
 82      '"cc': 'CNJ', 'nnp,': 'NP', 'sym\xc0\xa7\xb7': 'SYM', 
 83      'symc': 'SYM'} 
 84   
 85 -def simplify_indian_tag(tag): 
 86      if ':' in tag: 
 87          tag = tag.split(':')[0] 
 88      try: 
 89          tag = indian_mapping[tag.lower()] 
 90      except KeyError: 
 91          pass 
 92      return tag.upper() 
 93   
 94   
 95  ###################################################################### 
 96  #{ Alpino tags 
 97  ###################################################################### 
 98   
 99  alpino_mapping = { 
100      'noun':'N', 'name': 'NP', 'vg': 'VG', 'punct':'.', 
101      'verb':'V', 'pron': 'PRO', 'prep':'P' 
102      } 
103   
104 -def simplify_alpino_tag(tag): 
105      try: 
106          tag = alpino_mapping[tag] 
107      except KeyError: 
108          pass 
109      return tag.upper() 
110   
111  ###################################################################### 
112  #{ Default tag simplification 
113  ###################################################################### 
114   
115 -def simplify_tag(tag): 
116      return tag[0].upper() 
117