MATLAB - Repeat row n times (from A=[1;2;3] create B=[1;2;3;1;2;3;1;2;3])

Question

I would like to create, from the column matrix A=[1;2;3], another column matrix that repeats A n times. For example, being n=3, the new matrix would be B=[1;2;3;1;2;3;1;2;3]. Is there a way to to that (preferably without using loops)? Thank you.

score 4 · Accepted Answer · answered Mar 03 '17 at 20:16

4

You can use repmat it is a fantastic function:

repmat(A,[n,1])

The first value of the second parameter is repetitions in the first dimension (columns), the second in the second dimension (rows) etc.

answered Mar 03 '17 at 20:16

mpaskov

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Mendi Barel · Answer 2 · 2017-03-06T07:55:44.490

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Another way to do it:

A2=A(:,ones(1,n));
B=A2(:)

edited Mar 06 '17 at 07:55

answered Mar 03 '17 at 21:28

Mendi Barel

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This does replicate the vector `A` but not in the desired direction of the OP. – mpaskov Mar 03 '17 at 21:50
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I didn't noticed the column result. so i added some hack in the answer – Mendi Barel Mar 03 '17 at 22:15

score 0 · Answer 3 · answered Mar 03 '17 at 21:46

0

Another way is to do using padarray.

a = [1 2 3]
b = padarray(a, [2 0], 'post', 'circular')

post means add to the end of the array, circular pads with circular repetition of elements.

answered Mar 03 '17 at 21:46

smttsp

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MATLAB - Repeat row n times (from A=[1;2;3] create B=[1;2;3;1;2;3;1;2;3])

3 Answers3