Python创建字典多种方式

Posted 2021-01-16 target2018

1.创建空字典

1 >>> dic = {}
2 >>> type(dic)
3 <type ‘dict‘>

2.直接赋值创建

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

3.通过关键字dict和关键字参数创建

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

4.通过二元组列表创建

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

5.dict和zip结合创建

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

6.通过字典推导式创建

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

7.通过dict.fromkeys()创建

通常用来初始化字典, 设置value的默认值

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

8.其他

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