Random pick data by label

I have a data array (13x5). The last column is the class (1-4) of each data. How do I randomly pick n-number of data from each class? Let say 2 data from each class.

Answer 1

[Azzi Abdelmalek]

A=[randi(9,100,4) randi([1 4],100,1)]  % Example
[ii,jj,kk]=unique(A(:,5))
m=accumarray(kk,(1:numel(kk))',[],@(x) {x'})
out=cell2mat(cellfun(@(x) A(x(randperm(numel(x),2)),:),m,'un',0))