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。