python建立字典多種方式

標籤：python   dict   

1.建立空字典

>>> dic = {}>>> type(dic)<type ‘dict‘>

2.直接賦值建立

>>> dic = {‘spam‘:1, ‘egg‘:2, ‘bar‘:3}>>> dic{‘bar‘: 3, ‘egg‘: 2, ‘spam‘: 1}

3.通過關鍵字dict和關鍵字參數建立

>>> dic = dict(spam = 1, egg = 2, bar =3)>>> dic{‘bar‘: 3, ‘egg‘: 2, ‘spam‘: 1}

4.通過二元組列表建立

>>> list = [(‘spam‘, 1), (‘egg‘, 2), (‘bar‘, 3)]>>> dic = dict(list)>>> dic{‘bar‘: 3, ‘egg‘: 2, ‘spam‘: 1}

5.dict和zip結合建立

>>> dic = dict(zip(‘abc‘, [1, 2, 3]))>>> dic{‘a‘: 1, ‘c‘: 3, ‘b‘: 2}

6.通過字典推導式建立

>>> dic = {i:2*i for i in range(3)}>>> dic{0: 0, 1: 2, 2: 4}

7.通過dict.fromkeys()建立

通常用來初始化字典, 設定value的預設值

>>> dic = dict.fromkeys(range(3), ‘x‘)>>> dic{0: ‘x‘, 1: ‘x‘, 2: ‘x‘}

8.其他

>>> list = [‘x‘, 1, ‘y‘, 2, ‘z‘, 3]>>> dic = dict(zip(list[::2], list[1::2]))>>> dic{‘y‘: 2, ‘x‘: 1, ‘z‘: 3}

python建立字典多種方式