综合练习：词频统计

f=open("file.txt","r")
news=f.read()
f.close()
sep=‘‘‘,().;--‘‘‘
exclude={‘the‘,‘to‘,‘and‘,‘of‘,‘in‘,‘for‘,‘on‘,‘a‘,‘when‘,‘as‘,‘not‘,‘with‘,‘that‘}
for c in sep:
    news = news.replace(c,‘‘)
wordList=news.lower().split()
wordDict={}
wordSet=set(wordList)-exclude
for w in wordSet:
    wordDict[w]=wordList.count(w)
dictList = list(wordDict.items())
dictList.sort(key=lambda x:x[1],reverse=True)
for i in range(20):
    print(dictList[i])