Python 集合 pop()方法

Python的pop()方法从集合中弹出一个元素。它不接受任何参数，但返回弹出的元素。如果集合中不存在该元素，则会引发错误。下面是该方法的示例和签名。

语法

pop()

参数

无参数。

返回值

如果集合为空，则返回删除的元素或抛出错误。

让我们看一些pop()方法的例子，以了解它的功能。

示例1

一个简单的例子，使用pop()方法删除一个元素并修改集合。

# Python set pop() Method
# Creating a set
set = {1,2,3,4,5}
# Displaying elements
print(set) 
# Calling function
el = set.pop()
print("Element popped:",el)
print("Remaining elements: ",set)
el = set.pop()
print("Element popped:",el)
print("Remaining elements: ",set)
el = set.pop()
print("Element popped:",el)
print("Remaining elements: ",set)
el = set.pop()
print("Element popped:",el)
print("Remaining elements: ",set)

输出:

{1, 2, 3, 4, 5}
Element popped: 1
Remaining elements:  {2, 3, 4, 5}
Element popped: 2
Remaining elements:  {3, 4, 5}
Element popped: 3
Remaining elements:  {4, 5}
Element popped: 4
Remaining elements:  {5}

示例2

如果集合为空，则抛出KeyError错误给调用函数。请参见示例。

# Python set pop() Method
# Creating a set
set = {1,2}
# Displaying elements
print(set) 
# Calling function
el = set.pop()
print("Element popped:",el)
print("Remaining elements: ",set)
el = set.pop()
print("Element popped:",el)
print("Remaining elements: ",set)
el = set.pop()
print("Element popped:",el)
print("Remaining elements: ",set)

输出：

{1, 2}
Element popped: 1
Remaining elements:  {2}
Element popped: 2
Remaining elements:  set()
Traceback (most recent call last):
  File "main.py", line 13, in 
    el = set.pop()
KeyError: 'pop from an empty set'

示例3

该示例包含了按顺序添加和弹出元素来描述该方法的功能。

# Python set pop() Method
# Creating a set
set = {1,2}
# Displaying elements
print(set) 
# Calling function
el = set.pop()
print("Element popped:",el)
print("Remaining elements: ",set)
set.add(4)
el = set.pop()
print("Element popped:",el)
print("Remaining elements: ",set)
set.add(5)
el = set.pop()
print("Element popped:",el)
print("Remaining elements: ",set)

输出：

{1, 2}
Element popped: 1
Remaining elements:  {2}
Element popped: 2
Remaining elements:  {4}
Element popped: 4
Remaining elements:  {5}