Python学习笔记 --- 字典(六)

Python字典:
 
#字典可储存任意类型对象,以键值对展示:Key:value
#如 d = {key1:value1,key2:value2,...,keyn:valuen}
dict01= {'Name': 'Runoob', 'Age': 7, 'Class': 'First'}
print("dict01['Name']:",dict01["Name"])
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PS C:Usersadmin> & python e:/练习文档/python笔记/字典.py
dict01['Name']: Runoob
 
#删除字典元素
del dict01['Name'] #删除键“Name”;#del dict   删除字典(如果字典不存在会报异常)
print(dict01)
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PS C:Usersadmin> & python e:/练习文档/python笔记/输出.py
{'Class': 'First', 'Age': 7}

字典特性:字典值可以是任意的python对象,但是键不行;不允许同一个键出现两次,键必须不可变
 
 
#字典的内置函数
#radiansdict.clear()删除字典内所有元素
dict002={"asg":"asdhjjk","aa":"asd"}
dict002.clear()
print(dict002)
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PS C:Usersadmin> & python e:/练习文档/python笔记/输出.py
{}

 
#radiansdict.copy()返回一个字典的复制
dict003 = dict002.copy()
print(dict003)
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PS C:Usersadmin> & python e:/练习文档/python笔记/输出.py
{'asg': 'asdhjjk', 'aa': 'asd'}

#radiansdict.fromkeys(seq,value) 用于创建一个新字典,一序列seq中元素作为字典的键,value为字典所有键对应的初始值
 
seq=('name','age','sex')
dict=dict.fromkeys(seq,10])
print(dict) 
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PS C:Usersadmin> & python e:/练习文档/python笔记/输出.py
{'age': 10, 'sex': 10, 'name': 10}

#radiansdict.get(key,default=None)返回指定键的值,如果值不在字典中返回default值
mn={"asd":"asd","asda":"asdfaxz"}
print(mn.get("asd"))
print(mn.get("ffszxc","default"))

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PS C:Usersadmin> & python e:/练习文档/python笔记/输出.py
asd
default

 
#radiansdict.update(dict2)把字典dict2中得键/值对更新到dict中
dict001s={"ashd":"sdfa0","age":6}
dict002s={"sdfaxc":"sdxzcmne"}
dict001s.update(dict002s)
print(dict001s)
 
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PS C:Usersadmin> & python e:/练习文档/python笔记/输出.py
{'sdfaxc': 'sdxzcmne', 'ashd': 'sdfa0', 'age': 6}

 
#dict.items()以列表发返回可遍历得(键值)元组数组
print(dict001s.items())
 
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dict_items([('age', 6), ('sdfaxc', 'sdxzcmne'), ('ashd', 'sdfa0')])
 
 
#values()返回一个迭代器,可以使用list()来转换为列表,列表为字典中的所有值
print(list(dict001s.values()))
 
#pop(key)删除字典给定键key所对应的值,返回值为被删除的值。key值必须给出,否贼返回default值
 
dict001s.pop("age")
print(dict001s)
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[6, 'sdfa0', 'sdxzcmne']
{'ashd': 'sdfa0', 'sdfaxc': 'sdxzcmne'}

 
其他
#popitem 随机删除字典中的最后一个键和值
 
原文地址:https://www.cnblogs.com/liaolei123/p/13141481.html