python实现中文分词FMM算法实例

本文实例讲述了python实现中文分词FMM算法。分享给大家供大家参考。具体分析如下：

FMM算法的最简单思想是使用贪心算法向前找n个，如果这n个组成的词在词典中出现，就ok，如果没有出现，那么找n-1个...然后继续下去。假如n个词在词典中出现，那么从n+1位置继续找下去，直到句子结束。

import re
def PreProcess(sentence,edcode="utf-8"):
  sentence = sentence.decode(edcode)
  sentence=re.sub(u"[。，,！……!《》<>\"':：？\?、\|“”‘'；]"," ",sentence)
  return sentence
def FMM(sentence,diction,result = [],maxwordLength = 4,edcode="utf-8"):
  i = 0
  sentence = PreProcess(sentence,edcode)
  length = len(sentence)
  while i < length:
    # find the ascii word
    tempi=i
    tok=sentence[i:i+1]
    while re.search("[0-9A-Za-z\-\+#@_\.]{1}",tok)<>None:
      i= i+1
      tok=sentence[i:i+1]
    if i-tempi>0:
      result.append(sentence[tempi:i].lower().encode(edcode))
    # find chinese word
    left = len(sentence[i:])
    if left == 1:
      """go to 4 step over the FMM"""
      """should we add the last one? Yes, if not blank"""
      if sentence[i:] <> " ":
        result.append(sentence[i:].encode(edcode))
      return result
    m = min(left,maxwordLength)
    for j in xrange(m,0,-1):
      leftword = sentence[i:j+i].encode(edcode)
     #  print leftword.decode(edcode)
      if LookUp(leftword,diction):
        # find the left word in dictionary
        # it's the right one
        i = j+i
        result.append(leftword)
        break
      elif j == 1:
        """only one word, add into result, if not blank"""
        if leftword.decode(edcode) <> " ":
          result.append(leftword)
        i = i+1
      else:
        continue
  return result
def LookUp(word,dictionary):
  if dictionary.has_key(word):
    return True
  return False
def ConvertGBKtoUTF(sentence):
  return sentence.decode('gbk').encode('utf-8')
dictions = {}
dictions["ab"] = 1
dictions["cd"] = 2
dictions["abc"] = 1
dictions["ss"] = 1
dictions[ConvertGBKtoUTF("好的")] = 1
dictions[ConvertGBKtoUTF("真的")] = 1
sentence = "asdfa好的是这样吗vasdiw呀真的daf dasfiw asid是吗？"
s = FMM(ConvertGBKtoUTF(sentence),dictions)
for i in s:
  print i.decode("utf-8")
test = open("test.txt","r")
for line in test:
  s = FMM(CovertGBKtoUTF(line),dictions)
  for i in s:
    print i.decode("utf-8")

运行结果如下：

asdfa
好的
是
这
样
吗
vasdiw
呀
真的
daf
dasfiw
asid
是
吗
？

希望本文所述对大家的Python程序设计有所帮助。