Python dictionary adds a method to delete key values

How to add and delete key values ​​in python dictionary?

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Python dictionary (Dictionary) is a data type of mapping structure, consisting of no It consists of sequential "key-value pairs". The keys of the dictionary must be of immutable type, such as strings, numbers, and tuples; the values ​​can be any Python data type.

1. Create a new Python dictionary

>>> dict1={} #建立一个空字典

>>> type(dict1)  < type &#39;dict&#39;>

2. Add Python dictionary elements: two methods

>>> dict1['a']=1 #第一种  
>>> dict1  
{'a': 1}

#The second one: setdefault method

>>> dict1.setdefault('b',2)  
2  
>>> dict1  {'a': 1, 'b': 2}

3 ,Delete Python dictionary

#删除指定键－值对  
>>> dict1  
{'a': 1, 'b': 2}  
>>> del dict1['a'] #也可以用pop方法，dict1.pop('a')  
>>> dict1  
{'b': 2}  
#清空字典  
>>> dict1.clear()  
>>> dict1 #字典变为空了  
{}  
#删除字典对象  
>>> del dict1  
>>> dict1  Traceback (most recent call last):  
File "< interactive input>", line 1, in < module> 
NameError: name &#39;dict1&#39; is not defined

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