Delete many elements of list (python)

Question

I have a list L.

I can delete element i by doing:

del L[i]

But what if I have a set of non contiguous indexes to delete?

Answer 1

for i in I:
    del L[i]

won't work, because (depending on the order) you may invalidate the iterator -- this will usually show up as some items which you intended to delete remaining in the list.

It's always safe to delete items from the list in the reverse order of their indices. The easiest way to do this is with sorted():

for i in sorted(I, reverse=True):
    del L[i]