数据类型之字典

字典
帮助用户去表示一个事物的信息（事物是有多个属性）。
info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'} # 键值
# 请输出：我今天点%s,他的年龄是%s,性别是%s，他喜欢他的%s;
基本格式
data = {键:值,键:值,键:值,键:值,键:值,键:值,}

1. 独有功能

info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'}
keys，获取字典中所有的键。 ['name','age','gender','hobby']

for i in info.keys():
    print(i)

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
name
age
gender
hobby

values，获取字典中所有的值。 ['sundy','18','男','同桌']

info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'}
for i in info.values():
    print(i)

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
sundy
18
男
同桌

items，获取字典中的所有键值对

info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'}
for i in info.items():
    print(i)
 
D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
('name', 'sundy')
('age', 18)
('gender', '男')
('hobby', '同桌')

2. 公共功能
1.长度len
info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'}
print(len(info))

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
4

 

2.索引
info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'}
print(info['name'])
print(info['age'])

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
sundy
18

 

3.for循环
info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'}
for item in info.keys():   
print(item)

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
name
age
gender
hobby

info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'}
for item in info.values():   
print(item)

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
sundy
18
男
同桌

info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'}
for k,v in info.items():   
print(k,v)

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
name sundy
age 18
gender 男
hobby 同桌

 

4.修改（存在就修改/不存在就增加）
#修改键值
info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'}
info["name"]="amy"
print(info)

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
{'name': 'amy', 'age': 18, 'gender': '男', 'hobby': '同桌'}

info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'}
info["addr"]="beijing"
print(info)

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
{'name': 'sundy', 'age': 18, 'gender': '男', 'hobby': '同桌', 'addr': 'beijin
#修改键
删除后添加

 

删除（键值对）

info = {"name":'sundy','age':18,'gender':'男','hobby':'同桌'}
del info["name"]
print(info)

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
{'age': 18, 'gender': '男', 'hobby': '同桌'}

 

重点
数据类型嵌套：int bool str list tuple dict

list tuple dict可以多层嵌套：

val = (1,['sundy','a',1],{"k1":"a","k2":(2,3,"sundy")})
 
打印出(2,3,"sundy")中3
print(val[2]["k2"][1])

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
3

#在k2中第一个元素加入a
val = (1,['sundy','a',1],{"k1":"a","k2":[2,3,"sundy"]})
val[2]["k2"].insert(0,"a")
print(val)

D:\python3.6\python3.6.exe D:/python_code/day01/day05.py
(1, ['sundy', 'a', 1], {'k1': 'a', 'k2': ['a', 2, 3, 'sundy']}

 

总结：
字典的值可以为int bool str list tuple dict类型
字典的key：列表和字典不能为key，其他类型可以

列表，元组：有序
字典：无序（3.6之后字典有序）

 

 

来源：https://www.cnblogs.com/sundy08/p/11832049.html