[Python] Count the number of occurrences of elements in a sequence

import sys
import random
from collections import Counter
reload(sys)
sys.setdefaultencoding('utf-8')

Count the number of occurrences of an element using a dictionary

generate list

data_list=[random.randint(1,20)for _ in range(10)]
//从1-20随机选择10个数字

Generate statistics dictionary

data_dic=dict.fromkeys(data_list,0)
//选择生成的列表数字作为字典的键,0作为值

Statistics count

for x in data_list:
    data_dic[x]+=1
print data_dic

Use Counter to count directly

import library

from collections import Counter
//Counter不仅可以统计列表元素出现次数，还能统计字典元素出现次数，以及字符串中某个字母出现次数。并且还可以按照数量排序

Instructions

c1 = Counter(data_list)
//统计这个列表中元素出现的个数
print c1.most_common(3)
//打印这个列表中出现最多的前三个元素

c2=Counter(data_dict)
//使用方法同上

data_str='aaaabbcc1'
c3=Counter(data_str)
//使用方法同上

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