字典

一、dict 基本格式

① 大括号包括内容，"k1":'v1'为一对键值对
{
# "k1": 'v1', #键值对
# "k2": 'v2'
# }

② 布尔值(1,0)、列表、字典不能作为字典的key

③ 字典的value可以是任何值

④  字典无序

 

 

二、函数与用法

① 索引

dic = {'k1':'jio',"k2":123,"k3":'qqq','k999':(11,22,33),'kk2':{'oo1':666}}
v = dic['k1']
v2 = dic['kk2']['oo1']
print(v)
print(v2)

输出结果：

jio
666

② dict.fromkeys #根据序列，创建字典，并指定统一的值

v = dict.fromkeys(['k2',156,"554"],546)  #ke,156,554均为K值，546为v值
print(v)

输出结果：{156: 546, 'k2': 546, '554': 546}

 

③ .pop() #删除并获取值

dic = {'k1':'jio',"k2":123,"k3":'qqq'}
v= dic.pop('k1')
print(dic,v)

输出结果：{'k3': 'qqq', 'k2': 123} jio

 

    .popitem() #删除并获取值，默认删除最后一组

dic = {'k1':'jio',"k2":123,"k3":'qqq'}
k,v = dic.popitem()
print(dic)
print(k)
print(v)

输出结果：

{'k2': 123, 'k1': 'jio'}
k3
qqq

④ .get() #根据Key获取值，key不存在时，可以指定默认值（None）

dic = {'k1':'jio',"k2":123,"k3":'qqq'}
v = dic.get('k1')
print(v)
v2 = dic.get('k22',1234)
print(v2)

输出结果：

jio
1234

 

⑤ .setdefault() #设置值，

# 已存在，不设置，获取当前key对应的值
# 不存在，设置，获取当前key对应的值

dic = {'k1':'jio',"k2":123,"k3":'qqq'}
v = dic.setdefault('k13',77)
print(v)
v2 = dic.setdefault('k3')
print(v2)

输出结果：

77
qqq

 

⑥ .update() #更新

dic = {'k1':'jio',"k2":123,"k3":'qqq'}
dic.update({'k1':'OP',"K4":123,'K999':4})
print(dic)

输出结果：

{'k1': 'OP', 'K999': 4, 'k3': 'qqq', 'K4': 123, 'k2': 123}

dic = {'k1':'jio',"k2":123,"k3":'qqq'}
dic.update(k1=123,k4='abcdd',k000='ok')
print(dic)

输出结果：

{'k4': 'abcdd', 'k1': 123, 'k2': 123, 'k3': 'qqq', 'k000': 'ok'}

 

⑦ del #删除

dic = {'k1':'jio',"k2":123,"k3":'qqq','k999':(11,22,33),'kk2':{'oo1':666}}
del dic['kk2']['oo1']
print(dic)

输出结果：

{'k1': 'jio', 'k999': (11, 22, 33), 'k2': 123, 'k3': 'qqq', 'kk2': {}}

 

⑧ for循环 

dic = {'k1':'jio',"k2":123,"k3":'qqq','k999':(11,22,33),'kk2':{'oo1':666}}
for item in dic :
    print(item)

输出结果：

k2
k1
kk2
k999
k3

dic = {'k1':'jio',"k2":123,"k3":'qqq','k999':(11,22,33),'kk2':{'oo1':666}}
for item in dic.keys() : #输出K值
    print(item)

输出结果：

k2
k1
kk2
k999
k3

dic = {'k1':'jio',"k2":123,"k3":'qqq','k999':(11,22,33),'kk2':{'oo1':666}}
for item in dic.values() : #输出v值
    print(item)

输出结果：

123
{'oo1': 666}
qqq
(11, 22, 33)
jio