Python中 字典dict基本用法

 

创建字典

user_info={"name":"wang","age":"26","gender":"man"}
#我们用键值对来表示
key：name,age,gender
value:wang,26,man

 

clear(self)　　移除字典中所有的元素

 

user_info={"name":"wang","age":"26","gender":"man"}
user_info.clear()
print(user_info)
#输出：{}

 

 

 

get(self, k, d=None)　　根据k返回字典中所对应的值

 

user_info={"name":"wang","age":"26","gender":"man"}
str1= user_info.get("name")
print(str1)
#输出:wang

 

 

items(self)　　返回字典中所有的键值对

 

user_info={"name":"wang","age":"26","gender":"man"}
str1= user_info.items()
print(str1)
#输出：dict_items([('name', 'wang'), ('gender', 'man'), ('age', '26')])

 

 

 

keys(self)　　返回字典中所有的key

 

user_info={"name":"wang","age":"26","gender":"man"}
str1= user_info.keys()
print(str1)
#输出：dict_keys(['name', 'gender', 'age'])

 

values(self)　　返回字典中所有的value

 

 

user_info={"name":"wang","age":"26","gender":"man"}
str1= user_info.values()
print(str1)
#输出：dict_values(['26', 'wang', 'man'])

 

 

in 可见检查指定key是否在字典中

user_info={"name":"wang","age":"26","gender":"man"}
print("age" in  user_info.keys(）)
#输出：True

 

del：删除字典中的键值对

dic={"k1":11,"k2":22,"k3":33}
del dic["k2"]
print(dic)
#输出{'k1': 11, 'k3': 33}

#如果删除的key不在字典中那么就会报错
dic={"k1":11,"k2":22,"k3":33}
del dic["k5"]
print(dic)
#输出：KeyError: 'k5'

 

update(self, E=None, **F): 更新字典（个人感觉没什么卵用）

 

dic={"k1":11,"k2":22,"k3":33}
dic.update({"k1":11,"k2":22,"k3":33,"k4":55})
print(dic)
#输出：{'k2': 22, 'k4': 55, 'k3': 33, 'k1': 11}