rearranging the ind2sub result

I used [r,c] = ind2sub(size(matrix),idx) and the result gives me something like:

[r,c] =
1 1
2 1 
4 1 
5 1 
1 2 
3 2 
4 2 
5 2
etc.

It is arranged increasingly in the COLUMN part. Is it possible to do the opposite? (Increasing in the ROW part?)

Thanks

Answer 1

[Guillaume]

You can't get ind2sub to return values in a different order but you can sort the values afterward:

[r, c] = ind2sub(size(m), idx);
[r, order] = sort(r, 'stable');
c = c(order);

Another option is to put both r and c in the same matrix and use sortrows.

[rc(1), rc(2)] = ind2sub(size(m), idx);
rc = sortrows(rc);

[cgo]

'stable' doesn't seem to work. But it worked when I used 'ascend'. Thank you for your.

[Guillaume]

Sorry, I forgot that it's only unique that has a 'stable' option. Possibly, sort is already stable. In any case, 'ascend' is the default, so you don't need the 2nd argument.

Note that if sort is not stable (i.e. the order of c is not preserved for identical r), then the sortrows option is guaranteed to be.