Python_ collections_defaultdict默认字典

defaultdict(): 默认类型为字典，继承了字典的方法

import collections

dic = collections.defaultdict()

dic['k1'] = 'hello'

print(dic)

dic1 = collections.defaultdict(list)

dic1['k2'].append(34)
dic1['k2'].append(3)

print(dic1)

结果：

defaultdict(None, {'k1': 'hello'})

defaultdict(<class 'list'>, {'k2': [34,3]})