sample from data according to a class with no replacement

Lets say that I have a matrix n*m where n represented the instances while m representing the attributes. I have another column vector which is n*1 where n represents the classes corresponding to the enstances of the matrix n*m. Now, I want to sample from the matrix n*m based on the classes vector n*1. So, that for instance I want K instances with no replacement belonging to the class L. Any one could help me in that.

Answer 1

[MA]

I just solve it. So, for anyone who is looking for an answer, it is the following:

new_sample= datasample(X(T==L,:),K,'replace',false);