Question

What is the most pythonic way to truncate a list to N indices when you can not guarantee the list is even N length? Something like this:

l = range(6)

if len(l) > 4:
    l = l[:4]

I’m fairly new to python and am trying to learn to think pythonicly. The reason I want to even truncate the list is because I’m going to enumerate on it with an expected length and I only care about the first 4 elements.

Answer 1

All of the answers so far don’t truncate the list. They follow your example in assigning the name to a new list which contains the first up to 4 elements of the old list. To truncate the existing list, delete elements whose index is 4 or higher. This is done very simply:

del lst[4:]

Moving on to what you really want to do, one possibility is:

for i, value in enumerate(lst):
    if i >= 4:
        break
    do_something_with(lst, i, value)