python统计词频

arr = [1,2,3,4,5,6,4,5,2,3,6,8,9,6,5,3,6,2,4]
dic={}
for item in arr:
if item in dic.keys():
dic[item]+=1
else:
dic[item]=1
dic= sorted(dic.items(), key=lambda d:d[1], reverse = True)