python学习之字典

Posted 2020-08-19

1.字典

列表存储的数据比较单一也不够灵活，这时我们可以使用字典来存储某些多内容的数据

1.简单的字典

book={
    ‘huqiang‘:13457412571,
    ‘Jasper‘:110110110111,
    ‘despereado‘:784137611
}

View Code

输出结果：
{‘Jasper‘: 110110110111, ‘huqiang‘: 13457412571, ‘despereado‘: 784137611}
2.字典里嵌套字典

book_list={
    430424199103057689:{#字典里再加字典
        ‘name‘:"huqiang",#name是key，huqiang是value
        ‘age‘:"23",
        ‘addr‘:"hunan"
    },
    4304241991030571689: {
        ‘name‘: "huqiang",
        ‘age‘: "23",
        ‘addr‘: "hunan"
    },
    430424198903057689: {
        ‘name‘: "huqiang2",
        ‘age‘: "231",
        ‘addr‘: "hunan1"
    }
}
print(book_list)
#字典是key-value对应，自动去重，比列表存储信息更灵活

View Code

输出结果：

{430424199103057689: {‘age‘: ‘23‘, ‘name‘: ‘huqiang‘, ‘addr‘: ‘hunan‘}, 4304241991030571689: {‘age‘: ‘23‘, ‘name‘: ‘huqiang‘, ‘addr‘: ‘hunan‘}, 430424198903057689: {‘age‘: ‘231‘, ‘name‘: ‘huqiang2‘, ‘addr‘: ‘hunan1‘}}

3.取key对应的value值

print(book_list[430424199103057689])

输出结果：
{‘addr‘: ‘hunan‘, ‘age‘: ‘23‘, ‘name‘: ‘huqiang‘}

4.修改value值

book_list[430424199103057689][‘name‘]="abc"

print(book_list[430424199103057

)

输出结果：
{‘age‘: ‘23‘, ‘addr‘: ‘hunan‘, ‘name‘: ‘abc‘}
#提示：修改key值对应的value值，当key值不存在时会自动创建该值

book_list[430424199103057689][‘email‘]="40847394[email protected]"
print(book_list[430424199103057689])
输出结果：
{‘email‘: ‘[email protected]‘, ‘addr‘: ‘hunan‘, ‘name‘: ‘abc‘, ‘age‘: ‘23‘}

5.删除字典

del book_list[430424199103057689][‘age‘]   #key值后不指定删除名称则删除整个字典列
print(book_list[430424199103057689])
输出结果：
{‘name‘: ‘abc‘, ‘email‘: ‘[email protected]‘, ‘addr‘: ‘hunan‘}

6.获取字典key值

v=book_list.get(430424199103057689110) #这个key值不存在
print(v)
#Get获取值，存在 则显示，不存在则None
输出结果：
None

7.更新字典
定义一个新字典book_list2

book_list2={
    430424199103057689: {  
        ‘name‘: "111111111111",  #name对应的值修改为111111111111，其它值保持不变，原字典结构必须保持，不然会全部修改为新的字典
        ‘age‘: "23",
        ‘addr‘: "hunan"
    }
}
book_list.update(book_list2)

print(book_list[430424199103057689])

输出结果：
{‘addr‘: ‘hunan‘, ‘age‘: ‘23‘, ‘name‘: ‘111111111111‘}

8.输出Key和value值

print(book_list.keys())
#打印字典所有key
print(book_list.values())
#打印字典所有value

9.字典应用for循环
循环字典里的key值

for key in book_list:
    print(key)
输出结果：

430424199103057689
4304241991030571689
430424198903057689

循环字典的value值

for key in book_list:
    print(book_list[key])
输出结果：

{‘name‘: ‘111111111111‘, ‘addr‘: ‘hunan‘, ‘age‘: ‘23‘}
{‘name‘: ‘huqiang‘, ‘addr‘: ‘hunan‘, ‘age‘: ‘23‘}
{‘name‘: ‘huqiang2‘, ‘addr‘: ‘hunan1‘, ‘age‘: ‘231‘}

循环字典里的key对应的value值

for key in book_list:
    print(key,book_list[key])
输出结果：

430424199103057689 {‘name‘: ‘111111111111‘, ‘age‘: ‘23‘, ‘addr‘: ‘hunan‘}
4304241991030571689 {‘name‘: ‘huqiang‘, ‘age‘: ‘23‘, ‘addr‘: ‘hunan‘}
430424198903057689 {‘name‘: ‘huqiang2‘, ‘age‘: ‘231‘, ‘addr‘: ‘hunan1‘}