python 中文分词——FMM 算法

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，知道句子结束。

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')

测试代码：

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")

文本测试代码：

test = open("test.txt","r") for line in test: s = FMM(CovertGBKtoUTF(line),dictions) for i in s: print i.decode("utf-8")