Python Basic - 字典 (Dictionary) 的使用方法、相关操作、增删查改、嵌套，遍历、排序

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字典Dictory

• 通过key-value的形式存储数据。
• python 对key进行哈希计算，计算的结果是内存的地址用于存储value的值。
• 字典是无序存储。
• 字典的取值，存值通过哈希的结果进行存取
• 列表 其实类似C放言中说的数组，是一段连续的内存空间，查找，删除，插入数据时需要通过下标的偏移量进行处理，具有查找快。
• 字典不是连接的内存空间，而是将key进行哈希后得到内存地址进行存储。
• 因需要哈希存储，所以key必需唯一，如果key相同则得到同一个内存地址，将会冲突
• “key”必需是不可变的类型，像字符串，整型，元组等，像列表，字典是可变的类型，是不可哈希的。
• “value”可以是可变的类型，可以是列表，元组，或者 字典都可以。

创建一个字典

一个普通字典

dictory = {"name":"taohuadaozhu","age":30,"gendle":"male","company":"baidu","department":"IT"}

• dictory : 变量名
• ｛ ｝ ：使用大括号括起来
• "key":"value": 一个键值对中间使用冒号连接
• , 不同的键值对之间使用“,”隔开

一个嵌套字典

dictory = {"name":"taohuadaozhu","age":30,"gendle":"male","company":{"baidu":"Bigfirm","character":"Privately owned"},"department":"IT"}

dict() 函数来创建字典（不常用）

dictory = dict((("name","feihuang"),("age",30)))

• 一对key,value用一个（）括起来，也可以使用[ ]
• key与value之间使用“，”隔开
• 不同的key,value对儿用一个括号对儿括号括起来

字典操作

增

有两种方法：

直接增加

• 因为字典是无序的，所以不需要指定什么，只需要指定增加的key即可
• 如果键是已经存在的，则直接将value进行更改成新的指定的值

使用setdefault() 函数进行增加

• 如果增加的是新的key，则直接增加。
• 如果增加的是已经存在的key，则不会更改原来的值，相对安全
• setdefault() 方法是具有返回值的，可以保存到另外一个变量中用于返回是否成功修改等作用

dictory = {"name":"taohuadaozhu","age":30}
print(dictory)

#增加一对键值
dictory["company"]="baidu"
print(dictory)

#增加时键为已经存在的键,如果用此种方法，则是直接将原来的值 进行了更改
dictory["age"]=18
print(dictory)



#使用setdefault() 方法来增加
dictory.setdefault("department","IT")
print(dictory)

#使用setdefault() 函数对已经存在的key进行更改
dictory.setdefault("age",20)
print(dictory)

"""
{'name': 'taohuadaozhu', 'age': 30}
{'name': 'taohuadaozhu', 'age': 30, 'company': 'baidu'}
{'name': 'taohuadaozhu', 'age': 18, 'company': 'baidu'}
{'name': 'taohuadaozhu', 'age': 18, 'company': 'baidu', 'department': 'IT'}
{'name': 'taohuadaozhu', 'age': 18, 'company': 'baidu', 'department': 'IT'}
"""

删

del() 直接删除某个键下和值；如果直接跟字典，则整个字典都删除

dictory_baidu = {"name":"taohuadaozhu","age":30,"gendle":"male","company":{"baidu":"Bigfirm","character":"Privately owned"},"department":"IT"}
print(dictory_baidu)
del dictory_baidu["gendle"]
print(dictory_baidu)

dictory_baidu = {"name":"taohuadaozhu","age":30,"gendle":"male","company":{"baidu":"Bigfirm","character":"Privately owned"},"department":"IT"}
del dictory_baidu
print(dictory_baidu)

clear() 直接将所有的键值对儿全部清空，就留下一个空字典

dictory_baidu = {"name":"taohuadaozhu","age":30,"gendle":"male","company":{"baidu":"Bigfirm","character":"Privately owned"},"department":"IT"}
dictory_baidu.clear()
print(dictory_baidu)

pop() 将相应的键值对儿删除，将key所对应的value 做为返回值进行返回

dictory_baidu = {"name":"taohuadaozhu","age":30,"gendle":"male","company":{"baidu":"Bigfirm","character":"Privately owned"},"department":"IT"}
name = dictory_baidu.pop("name")
print(name)
print(dictory_baidu)

popitem() 随机删除对应的键值对儿，将key与value都做为元组方式做为返回值

dictory_baidu = {"name":"taohuadaozhu","age":30,"gendle":"male","company":{"baidu":"Bigfirm","character":"Privately owned"},"department":"IT"}
name = dictory_baidu.popitem()
print(name)
print(dictory_baidu)

查

.values() 查看所有的值

.keys() 查出所有的键

.items() 查看所有的键跟值，全部查出来

dictory = {"name":"taohuadaozhu","age":30,"gendle":"male","company":{"baidu":"Bigfirm","character":"Privately owned"},"department":"IT"}

#查出所有的键(key),但是查出来的并不是一个列表，但是可以转换成列表
print(dictory.keys())       			#查看dictory这个字典的所有的键
print(dictory.values())     			# 查看所有的value
print(dictory.items())      			#显示所有的键值对儿

print(type(dictory.keys())) 			#查看dictory.keys() 数据类型

dictory_key = list(dictory.keys()) 		#强制转换为列表，并将返回值 赋值给dictory_key这个变量
dictory_value = list(dictory.values())  #将values强制转换为列表

print(type(dictory_key))           		#查看dictory_key的数据类型，这里为list列表了。
print(type(dictory_value))           	#查看dictory_value的数据类型，这里为list列表了。


"""以下为输出内容
dict_keys(['name', 'age', 'gendle', 'company', 'department'])
dict_values(['taohuadaozhu', 30, 'male', {'baidu': 'Bigfirm', 'character': 'Privately owned'}, 'IT'])
dict_items([('name', 'taohuadaozhu'), ('age', 30), ('gendle', 'male'), ('company', {'baidu': 'Bigfirm', 'character': 'Privately owned'}), ('department', 'IT')])
<class 'dict_keys'>
<class 'list'>
<class 'list'>
"""

改

. update()

• 可以将一个字典update到另外一个字典中去，将一个字典合并到另外一个字典中去。
• 如果两个字典中的key有重复的，则将更新后的值覆盖更新前的值
• 如果原字典中没有的key，则加入到字典中去

dictory_baidu = {"name":"taohuadaozhu","age":30,"gendle":"male","company":{"baidu":"Bigfirm","character":"Privately owned"},"department":"IT"}
dictory_xiaomi = {"iname":"feihuang","iage":29,"gendle":"male","company_cn":"xiaomi","department":"IT"}
#修改其中一个值,与前面讲的增加一样，如果已经有的key，则改key所对应的值，如果没有这个key，则直接修改其内容
dictory_baidu["age"]=18
print(dictory_baidu)
print(dictory_xiaomi)

#使用update()方法对字典进行更新
dictory_baidu.update(dictory_xiaomi)    # 将dictory_xiaomi合并到dictory_baidu中去，如果已原字典中已经有相同的key了，则直接替换为dictory_xiaomi中对应的key的value，如果没有key，则直接合并过去
print(dictory_baidu)
print(dictory_xiaomi)

"""
{'name': 'taohuadaozhu', 'age': 18, 'gendle': 'male', 'company': {'baidu': 'Bigfirm', 'character': 'Privately owned'}, 'department': 'IT'}
{'iname': 'feihuang', 'iage': 29, 'gendle': 'male', 'company_cn': 'xiaomi', 'department': 'IT'}
{'name': 'taohuadaozhu', 'age': 18, 'gendle': 'male', 'company': {'baidu': 'Bigfirm', 'character': 'Privately owned'}, 'department': 'IT', 'iname': 'feihuang', 'iage': 29, 'company_cn': 'xiaomi'}
{'iname': 'feihuang', 'iage': 29, 'gendle': 'male', 'company_cn': 'xiaomi', 'department': 'IT'}
"""

其它操作

dict.fromkeys() : 指定多个key，然后统一赋值，可用于初始化

dictory = dict.fromkeys(["name1","name2","name3","name4"],"172.16.100.1")
print(dictory)
dictory = dict.fromkeys(["name1","name2","name3","name4"],["172.16.100.1","www.xiaomi.com"])
print(dictory)
"""
{'name1': '172.16.100.1', 'name2': '172.16.100.1', 'name3': '172.16.100.1', 'name4': '172.16.100.1'}
{'name1': ['172.16.100.1', 'www.xiaomi.com'], 'name2': ['172.16.100.1', 'www.xiaomi.com'], 'name3': ['172.16.100.1', 'www.xiaomi.com'], 'name4': ['172.16.100.1', 'www.xiaomi.com']}
"""

字典嵌套

字典内套着字典，但是也不限仅于此，也可以嵌套像列表，元组等都可以

dictory = {
    "Wudang":{
        "name":"ZhangSanfeng",
        "Age":103,
        "Skill":"Taiji"
    },
    "Emei":{
        "name": "Miejueshitai",
        "Age": 73,
        "Skill": "Emeijianfa"
    },
    "HuaShan":{
        "name": "Fengqingyang",
        "Age": 53,
        "Skill": "Dugujiujian"
    },
    "Mojiao":{
        "name": "Dongfangbubai",
        "Age": 63,
        "Skill": "xixingdafa"
    }
}
print(dictory)

“”“
#以下为输出的内容
{'Wudang': {'name': 'ZhangSanfeng', 'Age': 103, 'Skill': 'Taiji'}, 'Emei': {'name': 'Miejueshitai', 'Age': 73, 'Skill': 'Emeijianfa'}, 'HuaShan': {'name': 'Fengqingyang', 'Age': 53, 'Skill': 'Dugujiujian'}, 'Mojiao': {'name': 'Dongfangbubai', 'Age': 63, 'Skill': 'xixingdafa'}}
”“”

字典嵌套后内容的修改

dictory["Wudang"]["name"]="zhangwuji"
print(dictory)
"""
{'Wudang': {'name': 'zhangwuji', 'Age': 103, 'Skill': 'Taiji'}, 'Emei': {'name': 'Miejueshitai', 'Age': 73, 'Skill': 'Emeijianfa'}, 'HuaShan': {'name': 'Fengqingyang', 'Age': 53, 'Skill': 'Dugujiujian'}, 'Mojiao': {'name': 'Dongfangbubai', 'Age': 63, 'Skill': 'xixingdafa'}}

"""

字典排序

这里默认情况下是根据键进行排序，如需要根据值进行排序，可以"sorted(字典.value())"列表里面是根据值进行排序

字典遍历

• 一、只打印key

dictory_baidu = {"name":"taohuadaozhu","age":30,"gendle":"male","company":{"baidu":"Bigfirm","character":"Privately owned"},"department":"IT"}

for i in dictory_baidu:
    print(i)
print("==================================================")
"""
name
age
gendle
company
department
==================================================
"""

• 打印key与对应的value，此方法效率高

for i in dictory_baidu:
    print(i,dictory_baidu[i])
print("==================================================")
"""
name taohuadaozhu
age 30
gendle male
company {'baidu': 'Bigfirm', 'character': 'Privately owned'}
department IT
==================================================
"""

• 第二种方法打印key与对应的value，但是输出的是元组

for i in dictory_baidu.items():
    print(i)
print("==================================================")

"""
('name', 'taohuadaozhu')
('age', 30)
('gendle', 'male')
('company', {'baidu': 'Bigfirm', 'character': 'Privately owned'})
('department', 'IT')
==================================================
"""

• 第三种方法打印key与对应的value，使用两个变量输出

for i,v in dictory_baidu.items():
    print(i,v)
print("==================================================")

"""
name taohuadaozhu
age 30
gendle male
company {'baidu': 'Bigfirm', 'character': 'Privately owned'}
department IT
==================================================
"""