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。