通过弹出删除最后一个列表元素

Question

I have the following piece of Python code where I am trying to empty out list A by removing one element at a time starting from the end. I cannot seem to reduce the list to an empty one and I would like to know why not. Any insight would be extremely appreciated.

A = [3,4,5,6,2]
for i in A:
    A.pop()

Answer 1

var = [3,4,5,6,2]
for x in range(len(var)):
    a = var.pop(-1)
    print(a)

or reverse a list

var = var[::-1]

Answer 2

You can try this:

A = [3,4,5,6,2]

for a in range(len(A)):
    A.pop(-1)

Output:

>>> A
[]

You can also use a list comprehension instead of a traditional for loop:

A = [3,4,5,6,2]
[A.pop(-1) for a in range(len(A))]

Output:

>>> A
[]

Answer 3

Here you are trying to iterate through the elements of a list while the length of the list is reduced by 1 for each iteration.

This is not the right way to do this,

Try this,

A = [3,4,5,6,2]
for _ in range(len(A)):
    A.pop()

This will work.

Note: Never loop through a list in which you are going to perform some operations inside the loop-body. Try duplicating the list or use some other conditions.

Answer 4

This issue you are facing because you are trying to iterate the loop from first element and trying to remove the last element of the list. at one pint for loop runs out of element in a list hence it stops and you don't get empty list.

The proper solution will be to reverse iterate through the list and remove the elements.

Sample Code :

A = [3,4,5,6,2]
for i in range( len(A) -1 , -1, -1):
        A.pop()
        print (A)