python正向最大匹配分词和逆向最大匹配分词的实例

正向最大匹配

# -*- coding:utf-8 -*-

CODEC='utf-8'

def u(s, encoding):
  'converted other encoding to unicode encoding'
  if isinstance(s, unicode):
    return s
  else:
    return unicode(s, encoding)

def fwd_mm_seg(wordDict, maxLen, str):
  'forward max match segment'
  wordList = []
  segStr = str
  segStrLen = len(segStr)
  for word in wordDict:
    print 'word: ', word
  print "\n"
  while segStrLen > 0:
    if segStrLen > maxLen:
      wordLen = maxLen
    else:
      wordLen = segStrLen
    subStr = segStr[0:wordLen]
    print "subStr: ", subStr
    while wordLen > 1:
      if subStr in wordDict:
        print "subStr1: %r" % subStr
        break
      else:
        print "subStr2: %r" % subStr
        wordLen = wordLen - 1
        subStr = subStr[0:wordLen]
#      print "subStr3: ", subStr
    wordList.append(subStr)
    segStr = segStr[wordLen:]
    segStrLen = segStrLen - wordLen
  for wordstr in wordList:
    print "wordstr: ", wordstr
  return wordList

def main():
  fp_dict = open('words.dic')
  wordDict = {}
  for eachWord in fp_dict:
    wordDict[u(eachWord.strip(), 'utf-8')] = 1
  segStr = u'你好世界hello world'
  print segStr
  wordList = fwd_mm_seg(wordDict, 10, segStr)
  print "==".join(wordList)

if __name__ == '__main__':
  main()

逆向最大匹配

# -*- coding:utf-8 -*-

def u(s, encoding):
  'converted other encoding to unicode encoding'
  if isinstance(s, unicode):
    return s
  else:
    return unicode(s, encoding)

CODEC='utf-8'

def bwd_mm_seg(wordDict, maxLen, str):
  'forward max match segment'
  wordList = []
  segStr = str
  segStrLen = len(segStr)
  for word in wordDict:
    print 'word: ', word
  print "\n"
  while segStrLen > 0:
    if segStrLen > maxLen:
      wordLen = maxLen
    else:
      wordLen = segStrLen
    subStr = segStr[-wordLen:None]
    print "subStr: ", subStr
    while wordLen > 1:
      if subStr in wordDict:
        print "subStr1: %r" % subStr
        break
      else:
        print "subStr2: %r" % subStr
        wordLen = wordLen - 1
        subStr = subStr[-wordLen:None]
#      print "subStr3: ", subStr
    wordList.append(subStr)
    segStr = segStr[0: -wordLen]
    segStrLen = segStrLen - wordLen
  wordList.reverse()
  for wordstr in wordList:
    print "wordstr: ", wordstr
  return wordList

def main():
  fp_dict = open('words.dic')
  wordDict = {}
  for eachWord in fp_dict:
    wordDict[u(eachWord.strip(), 'utf-8')] = 1
  segStr = ur'你好世界hello world'
  print segStr
  wordList = bwd_mm_seg(wordDict, 10, segStr)
  print "==".join(wordList)

if __name__ == '__main__':
  main()

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