MATLAB: How to rearrange the rows of a matrix

Question

Hi, I want to reshape a matrix A of dimension rxc in a matrix B of the same dimension but with rows rearranged following the index in the first column

E.g.

 A=[ 1 1 4 7 10; 2 2 5 8 11; 3 3 6 9 12; 4 13 16 19 22; 5 14 17 20 23; 6 15 18 21 24; 1 25 26 27 28; 2 29 30 31 32; 3 33 34 35 36; 4 37 38 39 40; 5 41 42 43 44; 1 46 47 48 49; 2 50 51 52 53; 5 54 55 56 57; 6 58 59 60 61]

I want

B=[1 1 4 7 10; 1 25 26 27 28; 1 46 47 48 49; 2 2 5 8 11;2 29 30 31 32;2 50 51 52 53; 3 3 6 9 12; 3 33 34 35 36; 4 13 16 19 22; 4 37 38 39 40; 5 14 17 20 23; 5 41 42 43 44; 5 54 55 56 57; 6 15 18 21 24; 6 58 59 60 61]

The features of A on which I can rely are:

-the max of the first column is m=6;

-the elements in the first column of A are increasing until m and then they restart;

-each element of the first column of A can appear for at most n=3 times.

I prefer not to use loops.

Answer 1

The trick is to use the index from sorting the first column:

[~,idx] = sort(A(:,1));
B = A(idx,:);