Question

Is there a way to pass in N datasets and plot them in a line graph using for loop?
I did it by passing fixed number of parameter ( eg M1, M2, M3, M4), and repeat plotting manually like below. But I wonder if there are way to code the function dynamically? Let say I can pass in 4 datasets, or 40 datasets, and plot them in one graph via looping.

function plot_four_cdf(M1,M2,M3,M4)

[ycdf1,xcdf1] = cdfcalc(M1);
ycdf1 = ycdf1(2:length(ycdf1));
plot(xcdf1, ycdf1, '-+k', 'LineWidth', 1);

hold on;
[ycdf2,xcdf2] = cdfcalc(M2);
ycdf2 = ycdf2(2:length(ycdf2));
plot(xcdf2, ycdf2, '-ok', 'LineWidth', 1);
hold off;

hold on;
[ycdf3,xcdf3] = cdfcalc(M3);
ycdf3 = ycdf3(2:length(ycdf3));
plot(xcdf3, ycdf3, '-*k', 'LineWidth', 1);
hold off;

hold on;
[ycdf4,xcdf4] = cdfcalc(M4);
ycdf4 = ycdf4(2:length(ycdf4));
plot(xcdf4, ycdf4, '-sk', 'LineWidth', 1);

legend('M100','M80','M50','M20',...
   'Location','SE')

xlabel('Relative Error');
ylabel('CDF');
end

Answer 1

You can group all your data in a cell-array and pass that to the function:

function plot_cdfs(M)

    figure, hold on

    linestyles = {...
        '-+k', '-ok', '-*k', '-sk', ...
        '-+r', '-or', '-*r', '-sr');

    legendentries = cell(size(M));

    for ii = 1:numel(M)
        [ycdf, xcdf] = cdfcalc(M{ii});
        plot(xcdf, ycdf(2:end), linestyles{ii}, 'LineWidth', 1);
        legendentries{ii} = ['M' num2str(ii)];    
    end

    legend(legendentries{:}, 'Location','SE')

    xlabel('Relative Error');
    ylabel('CDF');

end

Note that M is constructed something like

M = {M1, M2, M3, ...} 

possibly also in a loop of its own. Note also that the legendentries are now kind of hard to define. You can pass them as a separate argument to the function (better option), or stuff them in the same cell array M next to the data they describe (not very portable).

Note also that you’d have to do some error checking (now, only 8 different plots can be made. An error will result if you do more).