#数据类型划分:可变数据类型,不可变数据类型
不可变数据类型:元组,bool int str 可哈希
可变数据类型:list,dict set 不可哈希
dict key 必须是不可变数据类型,可哈希,
value:任意数据类型。
dict 优点:二分查找去查询
存储大量的关系型数据
特点:无序的
dic = {
'name':['大猛','小孟'],
'py9':[{'num':71,'avg_age':18,},
{'num': 71, 'avg_age': 18, },
{'num': 71, 'avg_age': 18, },
],
True:1,
(1,2,3):'wuyiyi',
2:'二哥',
}
print(dic)
dic1 = {'age': 18, 'name': 'jin', 'sex': 'male',}
增
dic1['high'] = 185 #没有键值对,添加
dic1['age'] = 16 #如果有键,则值覆盖
dic1.setdefault('weight') # 有键值对,不做任何改变,没有才添加。
dic1.setdefault('weight',150)
dic1.setdefault('name','二哥')
print(dic1)
删
print(dic1.pop('age')) # 有返回值,按键去删除
print(dic1.pop('二哥',None)) # 可设置返回值
print(dic1)
print(dic1.popitem()) # 随机删除 有返回值 元组里面是删除的键值。
print(dic1)
del dic1['name1']
print(dic1)
del dic1
print(dic1)
dic1.clear() #清空字典
改 update
dic1['age'] = 16
dic = {"name":"jin","age":18,"sex":"male"}
dic2 = {"name":"alex","weight":75}
dic2.update(dic) #
print(dic)
print(dic2)
查
dic1 = {'age': 18, 'name': 'jin', 'sex': 'male',}
print(dic1.keys(),type(dic1.keys()))
print(dic1.values())
print(dic1.items())
for i in dic1:
print(i)
for i in dic1.keys():
print(i)
for i in dic1.values():
print(i)
a,b = 1,2
print(a,b)
赋值
a = 1
b = 2
a,b = b,a
print(a,b)
a,b = [1,2],[2,3]
a,b = (1,2)
print(a,b)
for k,v in dic1.items():
print(k,v)
v1 = dic1['name']
print(v1)
v2 = dic1['name1'] # 报错
print(v2)
print(dic1.get('name1','没有这个键'))