How to iterate over the first n elements of a list?


Say I’ve got a list and I want to iterate over the first n of them. What’s the best way to write this in Python?

Asked By: Bialecki



Python lists are O(1) random access, so just:

for i in xrange(n):
    print list[i]
Answered By: Michael Mrozek

I’d probably use itertools.islice (<- follow the link for the docs), which has the benefits of:

  • working with any iterable object
  • not copying the list


import itertools

n = 2
mylist = [1, 2, 3, 4]
for item in itertools.islice(mylist, n):



One downside is that if you wanted a non-zero start, it has to iterate up to that point one by one:

Tested in Python 3.8.6.

Answered By: MichaƂ Marczyk

The normal way would be slicing:

for item in your_list[:n]: 
Answered By: Mike Graham

You can just slice the list:

>>> l = [1, 2, 3, 4, 5]
>>> n = 3
>>> l[:n]
[1, 2, 3]

and then iterate on the slice as with any iterable.

Answered By: ezod
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