How to 'unfold' or 'reverse groupcounts?

Hey - is there a way to reverse a groupcount procedure?

I have a two column matrix describing the group number and group occurrence. I would like to convert this cummulative vector to a vector with a row for each occurrence:

[1 2;

2 1;

3 3;

4 1]

I would like to get

[1 1 2 3 3 3 4];

It is essentially reversing groupcounts.

Thanks - Adam

Answer 1

[Bruno Luong]

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

repelem(c(:,1).',c(:,2).')

[Adam]

Thanks - very elegant...

Adam