How do I select rows with particular step size?

Hi, I have a 25000 X 5 matrix. I need to select rows to create new subset of matrices with particular order of rows for e.g. 1,21,41,..., 2,22,42,....., 3,23,43,...and 20,40,60...... I would appreciate your input and thank you in advance.

Answer 1

[Mahdi]

If A is the 25000 X 5 matrix, then you can just use:

A(1:20:end, :)

to get 1,21,41,... from all of the columns. If you want data from just the first column, use

A(1:20:end, 1)

Look at what the : operator does to help you.

[Laliguras]

Thanks for quick response. It is exactly what I was looking for.