How to get all possible vectors of size n with elements [x,y]

Question

My question is similar to this one, but rather I want to find all possible vectors of a given size comprising [x,y,...] elements. For instance, given a list [1,2], how do I find all possible vectors with elements 1 and 2, with size 3? in this case it is:

(1,1,1)
(1,1,2)
(1,2,1)
(2,1,1)
(1,2,2)
(2,1,2)
(2,2,1)
(2,2,2)

What is an elegant way to do this? I'm imagining that subsequent for loops is not the best way to do this. In my real case I am actually looking for $2^{8}$ combinations since I am looking for vectors with 8 elements.

Nice guys, thanks. I knew about `itertools.combinations`, but couldn't get it to work. `itertools.product` solves the problem! — Sos, Sep 28 '20 at 15:21
@JohnColeman could you please add your answer, as it is better than mine. — Sos, Sep 28 '20 at 15:23
@Sos This is almost certainly a duplicate. I just wasn't in the mood to track down a good dup target for it. — John Coleman, Sep 28 '20 at 15:38
@JohnColeman sure, I understand. I did try searching for a similar question but wasn't lucky, but I also think it must've been asked before. — Sos, Sep 28 '20 at 15:54

score 0 · Answer 1 · answered Sep 28 '20 at 15:22

0

Thanks to the comments above, I got it working like so:

[x for x in itertools.product(*[x for x in ((1,2),)*3])]
#out:
[(1, 1, 1),
 (1, 1, 2),
 (1, 2, 1),
 (1, 2, 2),
 (2, 1, 1),
 (2, 1, 2),
 (2, 2, 1),
 (2, 2, 2)]

answered Sep 28 '20 at 15:22

Sos

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score 0 · Answer 2 · answered Sep 28 '20 at 15:26

The following does the work (it works well with 8 elemements too):

l=sum([list(set(itertools.permutations(i))) for i in list(itertools.combinations_with_replacement([1,2], 3))], [])
print(l)

Output:

[(1, 1, 1), (1, 2, 1), (2, 1, 1), (1, 1, 2), (1, 2, 2), (2, 2, 1), (2, 1, 2), (2, 2, 2)]

How to get all possible vectors of size n with elements [x,y]

2 Answers2