Pythonic way to iterate over multiple lists in a for loop?

Question

This seems pretty simple, but I haven't found a way to do it. I have three lists, a, b, and c. I want to iterate over all of them as if their elements altogether form one big list. I can think of a few ways to do this, but nothing very smooth or "pythonic". I expected the splat operator to work:

for e in (*a, *b, *c):
   # do stuff with e

but that gives a syntax error. Any ideas?

You can use [`itertools.chain`](https://docs.python.org/3/library/itertools.html#itertools.chain) — khelwood, Feb 08 '17 at 16:35
Actually, it would work in Python 3.5+. Still, you should use `itertools.chain`. — vaultah, Feb 08 '17 at 16:36

score 9 · Accepted Answer · answered Feb 08 '17 at 16:36

9

If they are all lists, all tuples, or all strings, then you can concatenate them:

for e in a + b + c:

For any combination of any iterables, including iterators like generators:

from itertools import chain

for e in chain(a, b, c):

answered Feb 08 '17 at 16:36

Alex Hall

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Pythonic way to iterate over multiple lists in a for loop?

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