list,tuple,dict,set常用方法

Posted 2020-08-26 welcome_home

Python中list,tuple,dict,set常用方法

 

collections模块提供的其它有用扩展类型

from collections import Counter
from collections import defaultdict


c = Counter()
for ch in \'programming\':
    c[ch] = c[ch]+1
dd = defaultdict(lambda:0)
dd[0]=dd[0]+1
print(dd[0])
print(c)

结果
-------------------------
1
Counter({\'g\': 2, \'m\': 2, \'r\': 2, \'n\': 1, \'i\': 1, \'a\': 1, \'p\': 1, \'o\': 1})

注意：defaultdict可以设置key不存在时的返回值(不报错)，而不像dict[]抛出异常