Python - 统计一篇文章中单词的频率

def frenquence_statistic(file_name):
    frequence = {}
    for line in open(file_name,'r').readlines():
        words =line.strip().split(" ")
        for word in words:
            word = ''.join(list(filter(str.isalpha,word))).lower()

            if frequence.get(word) == None :
                frequence[word] = 1
            else :
                frequence[word] +=1

    print (frequence)