Python创建字典的八种方式

Python创建字典的八种方式

1.创建空字典

dic = {}
type(dic)
# <type 'dict'>

2.直接赋值创建

dic = {'spam':1, 'egg':2, 'bar':3}
print(dic)
# {'bar': 3, 'egg': 2, 'spam': 1}

3.通过关键字dict和关键字参数创建

dic = dict(spam = 1, egg = 2, bar =3)
print(dic)
# {'bar': 3, 'egg': 2, 'spam': 1}

4.通过二元组列表创建

lis = [('spam', 1), ('egg', 2), ('bar', 3)]
dic = dict(lis)
print(dic)
# {'bar': 3, 'egg': 2, 'spam': 1}

5.dict和zip结合创建

dic = dict(zip('abc', [1, 2, 3]))
print(dic)
# {'a': 1, 'c': 3, 'b': 2}

6.通过字典推导式创建

dic = {i:2*i for i in range(3)}
print(dic)
# {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

dic = dict.fromkeys(range(3), 'x')
print(dic)
# {0: 'x', 1: 'x', 2: 'x'}

8.其他

lis = ['x', 1, 'y', 2, 'z', 3]
dic = dict(zip(lis[::2], lis[1::2]))
print(dic)
# {'y': 2, 'x': 1, 'z': 3}