pickTrainTest_2.m

function [Y_train, label_train, Y_test, label_test] = pickTrainTest_2(dataset, N_train_c)
    data_fn = fullfile('data', strcat(dataset, '.mat'))
    load(data_fn);
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%        
    %% ================== block: random projection ==========================
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%     fprintf('random projection...')
%     d_new = 3000;
%     A = randn(d_new, size(Y,1))        ;
%     Y = A*Y;


    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%        
    %% ------------------end of block: random projection ----------------------------
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%        


    Y = normc(Y);
    d = size(Y,1);
    if ~exist('Y_range', 'var')
        Y_range = label_to_range(label);
    end

    C = numel(Y_range) - 1;
    N_total = Y_range(C+1);
    N_train = C*N_train_c;
    N_test = N_total - N_train;

    Y_train = zeros(d, N_train);
    Y_test = zeros(d, N_test);
    label_train = zeros(1, N_train);
    label_test = zeros(1, N_test);
    %%
    cur_train = 0;
    cur_test = 0;
    for c = 1: C 
        Yc = get_block_col(Y, c, Y_range);
        N_total_c = size(Yc, 2);
        N_test_c = N_total_c - N_train_c;
        label_train(:, cur_train + 1: cur_train + N_train_c) = c*ones(1, N_train_c);
        label_test(:, cur_test + 1: cur_test + N_test_c) = c*ones(1, N_test_c);

        idx = randperm(N_total_c);

        Y_train(:, cur_train + 1: cur_train + N_train_c) = Yc(:, idx(1: N_train_c));
        Y_test(:, cur_test + 1: cur_test + N_test_c) = Yc(:, idx(N_train_c + 1: end));

        cur_train = cur_train + N_train_c;
        cur_test = cur_test + N_test_c;
    end 

    % d_new = 3000;
    % if size(Y,1) > d_new
    %     fprintf('pca...')
    %     [W,frac] = pcam(Y',d_new);
    %     Y_train = normc((Y_train'*W)');
    %     Y_test = normc((Y_test'*W)');      
    %     fprintf('DONE\n');
    % else
        Y_train = normc(Y_train);
        Y_test = normc(Y_test);
    % end
end