在Python中，在不创建新列表的情况下按索引从列表中删除元素的最佳方法是什么？

Question

I would like to remove all elements corresponding to an index from another list. For example,

my_lst = [100,200,300,400,500,600,700,800,900,1000]

I would like to remove the elements at indexes idxs = [1,3,9,6,4] .

What is the preferred way to do this under the constraint that the list itself should be modified (ie Do not generate a new list -- so no list comprehensions)?

Essentially, what is the closest I can come to for

del my_lst[idxs]

[100,300,600,700,800,900]

The problem is that when an item is deleted, the index shifts from that point on. So solutions such as this will not work. I have looked through other solutions too.

Answer 1

You can remove later indexes first so their position does not get shifted by removing smaller ones first:

my_lst = [0,100,200,300,400,500,600,700,800,900,1000]  # added 0 index number


# sort reversed: 9,6,4,3,1 
for i in sorted([1,3,9,6,4], reverse=True):
    del my_lst[i]

print(my_lst)

Output:

[0, 200, 500, 700, 800, 1000]

Answer 2

my_lst = [100,200,300,400,500,600,700,800,900,1000]

idxs = [1,3,9,6,4]

for i in range(0,len(idxs)):
    my_lst[idxs[i]]='d'

my_lst = [x for x in my_lst if x != 'd']