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字典相关的函数

作者:互联网

字典操作(字典里的键必须是唯一)

dict_1 ={'name':'shenzhen','age':'40','score':'90' }
print (dict_1)

 

1.往字典中添加键值对

dict["key"] = "value"

dic_1={"fruit":"orange","food":"meat","foods":"orange"} dic_1["city"]="shenzhen" print(dic_1)

 

setdefault()如果键不已经存在于字典中,将会添加键并将值设为默认值。

dic_1={"fruit":"orange","food":"meat","foods":"orange"}
dic_1.setdefault("name")
print(dic_1)

 #结果{'fruit': 'orange', 'food': 'meat', 'foods': 'orange', 'name': None}
dic_1={"fruit":"orange","food":"meat","foods":"orange"}
dic_1.setdefault("name","shenzhen")
print(dic_1)

#结果{'fruit': 'orange', 'food': 'meat', 'foods': 'orange', 'name': 'shenzhen'}

 

2.替换字典中指定键的值 dict["key"] = "value"

dic_1={"fruit":"orange","food":"meat","foods":"orange"}
dic_1["fruit"]="apple"
print(dic_1)

 

3.update()一个字典所有项追加到另一个字典里

dic_1={"fruit":"orange","food":"meat","foods":"orange"}
dic_2={"country":"china"}
dic_1.update(dic_2)
print(dic_1)
print("新字典:",dic_1)

print(dic_2)

 

4.字典取值 get()函数返回指定键的值,如果值不在字典中返回默认值。

dic_1={"fruit":"orange","food":"meat","foods":"orange"}
print(dic_1.get("fruit"))
print(dic_1.get("name"))#键不存在返回值为None
print("键返回的值是:%s" % dic_1.get("food"))
dic_1={"fruit":"orange","food":"meat","foods":"orange","zhongguo":{"guangdong":"shenzhen","guangxi":"nanning"}}
print(dic_1.get("zhongguo"))

 

5.keys()从字典中取出所有键,可通过 list() 来转换为列表

dic_1={"fruit":"orange","food":"meat","foods":"orange","zhongguo":{"guangdong":"shenzhen","guangxi":"nanning"}}
dic_2=dic_1.keys()
print(dic_2)
print(type(dic_2))

#通过list()方法转换为列表

print(list(dic_2))

 

 

6.values() 从字典中取出所有值,可以使用 list() 来转换为列表,列表为字典中的所有值

dic_1={"fruit":"orange","food":"meat","foods":"orange","zhongguo":"guangdong"}
dic_2=dic_1.values()
print(dic_2)

#通过list()方法转换为列表

list_1=list(dic_2)
print(list_1[3])

 

7.del 删除键值对

dic_1={"fruit":"orange","food":"meat","foods":"orange","zhongguo":"guangdong"}
del dic_1["fruit"] #删除对应的键值对
print(dic_1)

#可以通过del 删除整个字典
del dic_1

8.pop()删除字典给定键 key 所对应的值,返回值为被删除的值。
dic_1={"fruit":"orange","food":"meat","foods":"orange","zhongguo":"guangdong"}

print(dic_1.pop("fruit"))#返回值为"orange"
print(dic_1)

 

9.popitem()随机删除字典的键值对

dic_1={"fruit":"orange","food":"meat","foods":"orange","zhongguo":"guangdong"}
new_1=dic_1.popitem()

print(type(new_1))#返回值为包含被删除的键值对的一个元组
print(new_1)

print(dic_1)

 

10.clear()函数用于删除字典内所有元素,没有返回值。

dic_1={"fruit":"orange","food":"meat","foods":"orange","zhongguo":"guangdong"}
dic_1.clear()
print(dic_1)

 

11.copy()复制创建字典

dic_1={"fruit":"orange","food":"meat","foods":"orange","zhongguo":"guangdong"}
new_dic=dic_1.copy()
print("复制的新字典为:",new_dic)

 

12.in或not in检查字典是否有指定的键,有结果为 True,没有结果为 False

dic_1={"fruit":"orange","food":"meat","fruits":"orange","zhongguo":"guangdong"}
print("fruit" in  dic_1)

print("foods" not in dic_1)

 

标签:函数,food,dic,print,fruit,orange,相关,meat,字典
来源: https://www.cnblogs.com/wuya666/p/12620859.html