Python, match by index some lists into a list of lists

Question

So I have something like :

l1=[1,2,3]
l2=[4,5,6]
l3=[7,8,9]

Expected output is : ls=[[1,4,7],[2,5,8],[3,6,9]]

What it will be the most corect way to do that?

Writing code is probably the most correct way. – Maroun Jul 20 '16 at 14:19 — Maroun, Jul 20 '16 at 14:19

score 7 · Answer 1 · answered Jul 20 '16 at 14:21

7

Use zip and then list comprehension to turn the tuples into lists

[list(x) for x in zip(l1, l2, l3)]

Result:

[[1, 4, 7], [2, 5, 8], [3, 6, 9]]

answered Jul 20 '16 at 14:21

Božo Stojković

score 5 · Answer 2 · answered Jul 20 '16 at 14:21

5

>>> l1=[1,2,3]
>>> l2=[4,5,6]
>>> l3=[7,8,9]
>>> zip(l1, l2, l3)
[(1, 4, 7), (2, 5, 8), (3, 6, 9)]

The built-in function zip will help you with what you want.

answered Jul 20 '16 at 14:21

jia hilegass

3

You and Moses Koledoye answered at the same time, **exactly** (in seconds). That's the most satisfying thing that happened to me today. – Maroun Jul 20 '16 at 14:22
Moses Koledoye answered 6s before * – Gaetan Jul 20 '16 at 14:24
4

@Stages Nope http://stackoverflow.com/posts/38483818/timeline – Bhargav Rao Jul 20 '16 at 14:24
If you get the same amount of votes, I'll celebrate for the whole night. – Maroun Jul 20 '16 at 14:25
1

@Maroun Maroun how did you get the timeline pls? – Gaetan Jul 20 '16 at 14:29

score 5 · Answer 3 · answered Jul 20 '16 at 14:21

5

zip the three lists:

>>> l1 = [1,2,3]
>>> l2 = [4,5,6]
>>> l3 = [7,8,9]
>>> zip(l1,l2,l3)
[(1, 4, 7), (2, 5, 8), (3, 6, 9)]

Use a list comprehension to cast the tuples into lists to have a list of lists:

>>> [list(i) for i in zip(l1,l2,l3)]
[[1, 4, 7], [2, 5, 8], [3, 6, 9]]

answered Jul 20 '16 at 14:21

Moses Koledoye

The mention of the list comprehension and casting makes this the more valid answer – Samuel Jul 20 '16 at 14:24
3

Which I mentioned first, but oh well. :D – Božo Stojković Jul 20 '16 at 14:25
Looked like he posted first, but the timeline shows otherwise, either way the list comprehension is what OP is looking for – Samuel Jul 20 '16 at 14:26

3 Answers3