python(13)--字典（Dict）

news2025/2/22 16:07:13

一、字典的基本操作

1.定义字典

字典也是一个列表型的数据结构，字典的数据是用“{ }”装的（列表：[ ]，元组：( )），字典的元素是一一对应的关系“key-value”。

格式：

Dictname={ key1:value1,...,key2:value2}

#value是任何的python的对象

#字典的元素数量也是用len()函数

多说无益，直接看例子比较清晰：

实例：

flower={'rose':10,'orchid':16,'carnation':8}
tea={'红茶':30,'绿茶':20,'茉莉花茶':40}
print(flower)
print(tea)
print("字典flower的元素数量是：",len(flower))
print("字典的数据类型：",type(tea))

2.建立空字典

实例：

print("``````````````````````````````````````````````````````````")
flower={}
flower['rose']=13
flower['orchid']=16
print(flower)
print("``````````````````````````````````````````````````````````")

3.列出字典元素的值

格式：

flower【'rose'】

#注意列出字典元素的值要用中括号哦“[ ]”

#上面语句表达的意思是字典 flower 的 rose（key）的对应 10（value）值。

实例：

print("``````````````````````````````````````````````````````````")
flower={'rose':10,'orchid':16,'carnation':8}
tea={'红茶':30,'绿茶':20,'茉莉花茶':40}
print("一支玫瑰的价钱是：",flower['rose'])
print("红茶一袋的价钱是：",tea['红茶'])
print("``````````````````````````````````````````````````````````")

如果有两个“rose”，两个“红茶”呢，元素对应的值（value）是哪个呢？

print("``````````````````````````````````````````````````````````")
flower={'rose':10,'orchid':16,'carnation':8,'rose':15}
tea={'红茶':30,'绿茶':20,'茉莉花茶':40,'红茶':13}
print("一支玫瑰的价钱是：",flower['rose'])
print("红茶一袋的价钱是：",tea['红茶'])
print("``````````````````````````````````````````````````````````")

如上所示，字典中的元素对应值被后面的值占领了。

4.增加字典元素

实例：

print("``````````````````````````````````````````````````````````")
flower={'rose':10,'orchid':16,'carnation':8}
tea={'红茶':30,'绿茶':20,'茉莉花茶':40}
flower['tuilp']=13
print(flower)

print("``````````````````````````````````````````````````````````")

5.更改元素内容

实例：

print("``````````````````````````````````````````````````````````")
flower={'rose':10,'orchid':16,'carnation':8}
tea={'红茶':30,'绿茶':20,'茉莉花茶':40}
flower['rose']=13
print(flower)
print("``````````````````````````````````````````````````````````")

6.删除字典（特定元素）

删除元素实例：

print("``````````````````````````````````````````````````````````")
flower={'rose':10,'orchid':16,'carnation':8}
tea={'红茶':30,'绿茶':20,'茉莉花茶':40}
del flower['rose']
print(flower)
print("``````````````````````````````````````````````````````````")

删除字典实例：

print("``````````````````````````````````````````````````````````")
flower={'rose':10,'orchid':16,'carnation':8}
del flower
print(flower)
print("``````````````````````````````````````````````````````````")

7. 字典的复制

print("``````````````````````````````````````````````````````````")
flower={'rose':10,'orchid':16,'carnation':8}
copyflower=flower.copy()
print(flower)
print(copyflower)
print("``````````````````````````````````````````````````````````")

二、遍历字典

1.遍历字典的key-value

flower={'rose':10,
        'orchid':16,
        'carnation':8}
for flowers,price in flower.items():
    print("花名：",flowers)
    print("价格：",price)
    print("\n")

2.遍历字典的键(key)

flower={'rose':10,
        'orchid':16,
        'carnation':8}
for flowers in flower.keys():
    print("花名：",flowers)
    print("\n")

没有keys()函数也行：

flower={'rose':10,
        'orchid':16,
        'carnation':8}
for flowers in flower:
    print("花名：",flowers)

3.遍历字典的值（value）

flower={'rose':10,
        'orchid':16,
        'carnation':8}
for flowers in flower.values():
    print("价格：",flowers)

4.字典里面放字典

实例：人物介绍

role={

    '鲁班':{
        '技能':'土木建筑',
        '职业':'工匠'
    },
    '钟无艳':{
        '技能':'出谋划策',
        '职业':'中国古代四大丑女之一'
    },
    '蔡文姬':{
        '技能':'琴棋书画',
        '职业':'董祀之妻'
    }

}
for a,b in role.items():
    print("姓名：",a)
    print("介绍：",b)