字典

字典

定义

字典 -- dict

字典是无序的,可变的数据类型

字典:用于存储数据,存储大量数据,字典要比列表快,将数据和数据之间进行关联

定义一个字典:

dic = {"常鑫":10,"李文虎":80,"张宇":100}
字典中逗号分隔叫做一个元素"常鑫"(键):10(值) -- 键值对

dic = {"常鑫":10,"李文虎":80,"张宇":100,10:"大黑哥",True:123,(1,2,3):"大煎饼",[1,2]:"meet"}
print(dic)

字典的键:

可哈希的 --- 不可变的数据类型 --- 避免哈希冲突使用了 开放寻址法

不可哈希的 --- 可变的数据类型

要求唯一 --- 如果有重复的后边值的将前面的值覆盖

字典的值:

可以任意

字典的增,删,改,查

增:

dic = {"常鑫":10,"李文虎":80,"张宇":100}
dic["李文虎"] = 89       
print(dic)               # dic = {"常鑫":10,"李文虎":89,"张宇":100}
 # 暴力添加

dic = {"常鑫":10,"李文虎":80,"张宇":100}
dic.setdefault("大黑哥",50)      
print(dic)   # {'常鑫': 10, '李文虎': 80, '张宇': 100, '大黑哥': 50}
# "大黑哥"这个键去字典查询,没有就添加,有就不执行添加.

删除:

dic = {"常鑫":10,"李文虎":80,"张宇":100}
del dic["常鑫"]
prin(dic)                # {'李文虎': 80, '张宇': 100}
# 通过字典的键删除键值对

dic = {"常鑫":10,"李文虎":80,"张宇":100}
print(dic.pop("常鑫"))           # 10
print(dic)                      # {'李文虎': 80, '张宇': 100}
# 通过字典的键进行删除键值对 返回值:返回的是删除的值

dic = {"常鑫":10,"李文虎":80,"张宇":100}
dic.clear()
print(dic)            #{}
# 清空

改:

dic = {"常鑫":10,"李文虎":80,"张宇":100}
dic["常鑫"] = "dsb"
print(dic)             # {'常鑫': 'dsb', '李文虎': 80, '张宇': 100}
# 字典中没有某个键值对的时候就是添加,当键在字典中存在的时候就是修改
# 有则改,无则加

dic = {"常鑫":10,"李文虎":80,"张宇":100}
dic.update({"常鑫":50,"张宇":30})
print(dic)            # {'常鑫': 50, '李文虎': 80, '张宇': 30}
# update括号中的字典级别高于update前面的字典

查:

dic = {"常鑫":10,"李文虎":80,"张宇":100}
for i in dic:
    print(i)
    # 常鑫
    # 李文虎
    # 张宇
#循环获取的是字典中每个键值对的键

dic = {"常鑫":10,"李文虎":80,"张宇":100}
print(dic.get("李文虎"))     # 80
# 通过键获取值,如果将不存在字典中返回None

print(dic["ck"])            # 报错
# 通过键获取值,如果将不存在字典中报错

其他操作

dic = {"1":3,"5":9,"李文虎":100}
for i in dic:
    print(i,dic.get(i))             
# 1 3
# 5 9
# 李文虎 100
# 获取字典中所有的键和值

dic = {"1":3,"5":9,"李文虎":100}
print(dic.keys())       # dict_keys(['1', '5', '李文虎'])
# 高仿列表 -- dict_keys(['1', '5', '李文虎']) 支持for循环 不支持索引

dic = {"1":3,"5":9,"李文虎":100}
for i in dic.keys():
     print(i)                   # 1
                                # 5
                                # 李文虎
# 获取字典中所有的键

dic = {"1":3,"5":9,"李文虎":100}
lst = []
for i in dic:
    lst.append(dic[i])
print(lst)                       #[3, 9, 100]
# 获取字典中所有的值

print(list(dic.values()))        #[3, 9, 100]
# 获取字典中所有的值

dic = {"1":3,"5":9,"李文虎":100}
print(dic1.items())
# dict_items([('1', 3), ('5', 9), ('李文虎', 100)])

dic = {"1":3,"5":9,"李文虎":100}
for i in dic.items():
    print(i[0],i[1])           # 1 3
                               # 5 9
                               # 李文虎 100

解构

a,b = 10,12
print(a)
print(b)                 # 10  
                         # 12
    
    
a = 10
b = 20
a,b = b,a
print(a,b)               # 20 10
                           
a,b = [1,2]
print(a,b)               # 1 2

a,b = (3,4)
print(a,b)               # 3 4

a,_,b = (3,4,5)
print(a,b)               # 3 5  等号后边的值和前面的变量名要一一对应

a = 10,12               
print(a)                 # (10,12)  本质就是一个元组

a,b = "23"
print(a,b)               # 2 3

a,b = {"1":"a","2":"b"}
print(a,b)               # 1 2 

dic = {"1":3,"5":9,"李文虎":100}
for i in dic.items():
    print(i)             # ('1', 3)
                         # ('5', 9)
                         # ('李文虎', 100)
            
dic = {"1":3,"5":9,"李文虎":100}
for k,v in dic.items():
    print(k,v)           # 1 3
                         # 5 9
                         # 李文虎 100
# 获取每个元素的键和值

字典的嵌套

dic = {1001:["周杰伦","林俊杰"],
       1002:{"汪峰":{"前妻1":["大烧饼"],"前妻2":["熊大","熊二"],"国际章":"肉丝"}},
       1003:{"陈冠希":["阿娇","阿萨","张柏芝"]},
       1004:{"韦小宝":[{"教主夫人":["教主"]},{"阿珂":"刺客"},{"双儿":"天地会"}, {"爱心觉罗建宁":"公主"}, {"独臂神尼":{"韦小宝师父":{"兰陵王":"隐身"},"花木兰":[ "唧唧复唧唧","木兰是战士",{"爸爸":["花和尚"]}]}}, {"陈圆圆":"丈母娘"},{"穆建平":"小郡主"}]},
       1005:{"常鑫":["大黑哥","大烧饼","吃大煎饼","肉夹馍","自行车","井盖",]}
       }

	找到"教主"
    print(dic[1004]["韦小宝"][0]["教主夫人"][0])
    找到"井盖"
    print(dic[1005]["常鑫"][-1])
    找到"熊二"
    print(dic[1002]["汪峰"]["前妻2"][-1])
    找到"隐身"
    print(dic[1004]["韦小宝"][4]["独臂神尼"]["韦小宝师父"]["兰陵王"])
    找到"花和尚"
    print(dic[1004]["韦小宝"][4]["独臂神尼"]["花木兰"][2]["爸爸"][0])