Python 删除字典项

使用 del 关键字

Python 的 del 关键字可以从内存中删除任何对象。在这里我们使用它来删除字典中的键值对。

语法

del dict['key']

示例

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'}

示例

使用del关键字与字典对象本身一起，可以将其从内存中移除。

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()方法会从字典中移除指定键对应的元素。

语法

val = dict.pop(key)

返回值

pop()方法在移除键值对之后返回指定键的值。

示例

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 output −

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()方法不接受任何参数。它弹出最后插入的键值对，并以元组形式返回。

语法

val = dict.popitem()

返回值

popitem()方法返回一个包含从字典中移除的项的键和值的元组。

示例

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)

它将会产生以下的 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()方法会将字典对象中的所有元素删除，并返回一个空对象。

语法

dict.clear()

示例

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: 
 {}