Create a matrix using elements of other vectors in matlab

Question

I have two vectors a, b

a=[1; 2; 3; 4]
b=[1; 2; 3]

And I want to create a matrix which will look like this

c=[1 1; 2 1; 3 1; 4 1; 1 2; 2 2; 3 2; 4 2; 1 3; 2 3; 3 3; 4 3]

possible duplicate of [Matlab - Generate all possible combinations of the elements of some vectors](http://stackoverflow.com/questions/4165859/matlab-generate-all-possible-combinations-of-the-elements-of-some-vectors) — Amro, Jun 29 '12 at 16:03

score 4 · Accepted Answer · answered Jun 28 '12 at 08:30

4

Here is yet another way!

c = [repmat(a,numel(b),1),sort(repmat(b,numel(a),1))]

answered Jun 28 '12 at 08:30

Not Bo Styf

Andrey Rubshtein · Answer 2 · 2012-06-28T08:52:32.273

3

I have a feeling that there is a much better way, still...

p1 = repmat(a,[numel(b),1]);
p2 =  imresize(b,[numel(a)*numel(b) 1],'nearest');
answer =  [p1 p2];

Found a better way:

 [A,B] = meshgrid(a,b);
 answer = [reshape(B,[],1) reshape(A,[],1)];

Chris Taylor suggests a more compact way:

 [A B]=meshgrid(a,b); [B(:) A(:)];

edited Jun 28 '12 at 08:52

answered Jun 28 '12 at 07:56

Andrey Rubshtein

1

Even better: `[A B]=meshgrid(a,b); [B(:) A(:)]` – Chris Taylor Jun 28 '12 at 08:40
1

I always use `ndgrid` - the output order makes so much more sense. – Jonas Jun 28 '12 at 12:54

2 Answers2