python关于字符串和列表计数

1. 新建哈希表（字典），循环遍历计数。

// 哈希表（字典）计数
def counter(s):
	hash = {
   }
	# for index,item in enumerate(s):
	for item in s:
		if item in hash:
			hash[item] = hash[item] + 1
		else:
			hash[item] = 1
	return hash

if __name__ == '__main__':
	s1 = [1,2,3,2,1,1,1,1,1,1]
	s2 = 'abcaaaaabcc'
	print(counter(s1))
	print(counter(s2))

【输出】
{1: 7, 2: 2, 3: 1}
{‘a’: 6, ‘c’: 3, ‘b’: 2}

2. 库函数。

// 库函数计数
from collections import Counter
def counter_1(s1,s2):
	return Counter(s1) + Counter(s2)
	
def counter_2(s1):
	return s1.count(1)

if __name__ == '__main__':
	s1 = [1,2,3,2,1,1,1,1,1,1]
	s2 = 'abcaaaaabcc'
	print(counter_1(s1, s2))
	print(counter_2(s1))

Counter({1: 7, ‘a’: 6, ‘c’: 3, 2: 2, ‘b’: 2, 3: 1})
7