#字典是一系列键值对。每个键都与一个值相关联,可以使用键来访问与之相关联的值。值可以是数字、字符串、列表和字典。事实上,可将任何python对象用作字典中的值。比如:
"""color和point是键,green和5是值。键和值之间用冒号:"""
alien_0={
"color":"green",
"points":5,
}
#访问字典中的值,比如:
print(alien_0["color"])
print(alien_0["points"])
#添加字典的键值对,比如:
alien_0["x_position"]=0
alien_0["y_position"]=25
print(alien_0)
#修改字典中的值,比如:
print("alien_0字典的color键之前的颜色是:"+alien_0["color"])
alien_0["color"]="yellow"
print("alien_0字典的color键修改之后的颜色是:"+alien_0["color"])
#使用del删除键值对,必须指定字典名和要删除的键。注意:删除的键值对永远消失,无法恢复。比如:
del alien_0["color"]
print(alien_0)
#遍历字典的所有键值对,方法:字典名.items(),比如:
user_0={
"username":"rose",
"first":"jack",
"second":"tony",
"last":"rose",
}
for key,value in user_0.items():
print("\n键:"+key)
print("值:"+value)
#遍历字典的所有键,方法:字典名.keys(),比如:
for key in user_0.keys():
print("键:"+key)
#按顺序遍历字典中所有的键,比如:
for key in sorted(user_0.keys()):
print("顺序键:"+key)
#遍历字典的所有值,方法:字典名.values(),比如:
for value in user_0.values():
print("值:"+value)
#为了剔除重复值,使用set()集合,保证值都是独一无二的【键是不可能重复的】。比如:
for value in set( user_0.values()):
print("剔除重复值:"+value)
#嵌套:字典列表,比如:
alien_0={"color":"green","points":6}
alien_1={"color":"yellow","points":10}
alien_2={"color":"red","points":16}
aliens=[alien_0,alien_1,alien_2]
for alien in aliens:
print(alien)
#嵌套:将列表存储在字典中,比如:S
pizza={
"crust":"thick",
"toppings":["mushroom","extra cheese"]
}
for topping in pizza["toppings"]:
print(topping)
#嵌套:在字典中存储字典,比如:
users={
"rose":{
"sex":"女",
"age":"22",
"location":"American",
},
"jack":{
"sex":"男",
"age":"23",
"location":"American",
},
}
for key,value in users.items():
print(key+"的信息:")
print("性别:"+value["sex"]+",年龄:"+value["age"]+",所属地:"+value["location"])