Python - 删除字典项

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使用 del 关键字

Python 的del关键字从内存中删除任何对象。这里我们用它来删除字典中的键值对。

句法

del dict['key']

例子

numbers = {10:"Ten", 20:"Twenty", 30:"Thirty",40:"Forty"}
print ("numbers dictionary before delete operation: \n", numbers)
del numbers[20]
print ("numbers dictionary before delete operation: \n", numbers)

它将产生以下输出-

numbers dictionary before delete operation:
 {10: 'Ten', 20: 'Twenty', 30: 'Thirty', 40: 'Forty'}
numbers dictionary before delete operation:
 {10: 'Ten', 30: 'Thirty', 40: 'Forty'}

例子

del 关键字与 dict 对象本身将其从内存中删除。

numbers = {10:"Ten", 20:"Twenty", 30:"Thirty",40:"Forty"}
print ("numbers dictionary before delete operation: \n", numbers)
del numbers
print ("numbers dictionary before delete operation: \n", numbers)

它将产生以下输出-

numbers dictionary before delete operation:
 {10: 'Ten', 20: 'Twenty', 30: 'Thirty', 40: 'Forty'}
Traceback (most recent call last):
 File "C:\Users\mlath\examples\main.py", line 5, in <module>
  print ("numbers dictionary before delete operation: \n", numbers)
                                                           ^^^^^^^
NameError: name 'numbers' is not defined

使用 pop() 方法

dict 类的 pop() 方法会导致从字典中删除具有指定键的元素。

句法

val = dict.pop(key)

返回值

pop() 方法在删除键值对后返回指定键的值。

例子

numbers = {10:"Ten", 20:"Twenty", 30:"Thirty",40:"Forty"}
print ("numbers dictionary before pop operation: \n", numbers)
val = numbers.pop(20)
print ("nubvers dictionary after pop operation: \n", numbers)
print ("Value popped: ", val)

它将产生以下输出-

numbers dictionary before pop operation: 
 {10: 'Ten', 20: 'Twenty', 30: 'Thirty', 40: 'Forty'}
nubvers dictionary after pop operation: 
 {10: 'Ten', 30: 'Thirty', 40: 'Forty'}
Value popped:  Twenty

使用 popitem() 方法

dict() 类中的 popitem() 方法不带任何参数。它弹出最后插入的键值对，并返回与元组相同的值

句法

val = dict.popitem()

返回值

popitem() 方法返回一个元组，其中包含从字典中删除的项目的键和值

例子

numbers = {10:"Ten", 20:"Twenty", 30:"Thirty",40:"Forty"}
print ("numbers dictionary before pop operation: \n", numbers)
val = numbers.popitem()
print ("numbers dictionary after pop operation: \n", numbers)
print ("Value popped: ", val)

它将产生以下输出-

numbers dictionary before pop operation: 
 {10: 'Ten', 20: 'Twenty', 30: 'Thirty', 40: 'Forty'}
numbers dictionary after pop operation: 
 {10: 'Ten', 20: 'Twenty', 30: 'Thirty'}
Value popped:  (40, 'Forty')

使用clear()方法

dict 类中的clear() 方法从字典对象中删除所有元素并返回一个空对象。

句法

dict.clear()

例子

numbers = {10:"Ten", 20:"Twenty", 30:"Thirty",40:"Forty"}
print ("numbers dictionary before clear method: \n", numbers)
numbers.clear()
print ("numbers dictionary after clear method: \n", numbers)

它将产生以下输出-

numbers dictionary before clear method: 
 {10: 'Ten', 20: 'Twenty', 30: 'Thirty', 40: 'Forty'}
numbers dictionary after clear method: 
 {}