matlab - Dynamic Legend (Updates in every recursion)

Question

I got a for i=1:15. Inside I generate a variable d=1:0.01:10, which is the x'x axis and based on this, I create a continuous function F(d) which has 2 unique variables pitch and yaw. I then plot this using different colors in every recursion using cmap = hsv(15);. So then it is:

d=1:0.01:10;
cmap = hsv(15);

for i=1:15
    pitch = unidrnd(10);
    yaw   = unidrnd(10);

    for j=1:length(d)
        F(j) = d(j)*3*pitch*yaw; %// some long calculation here
    end

    p1 = plot(d,F,'Linewidth', 1.0);
    title ('blah blah')
    set(p1, 'Color', cmap(i,:));
    hold on;
    legend (['pitch,yaw:', num2str(pitch) num2str(yaw)]) 
end 
hold off;

This code updates the unique pitch, yaw values in every recursion (without space between them so it is kind irritating) but fails to:

1. Apply the proper color, visible in the figure.
2. Hold the color from the previous iteration and the values of pitch,yaw.

Answer 1

Semidocumented Solution

Adding lines to a legend in a loop can be accomplished with "dynamic legends", as described on undocumentedmatlab.com.

The idea is to replace the legend command with:

legend('-DynamicLegend');

Then update the plot command with a DisplayName parameter:

plot(d,F,'Linewidth',1.0,'DisplayName',sprintf('pitch,yaw: %d,%d',pitch,yaw));

Then plots that are added to the axes get added to the legend:

If semi-documented features are not your cup of tea, use the DisplayName trick and simply toggle the legend off/on. That is, instead of -DynamicLegend:

legend('off'); legend('show');

A different variation that does not use either DisplayName or -DynamicLegend is to delete and recreate the legend with an array of stored strings.

Official Solution

The official solution recommended by MathWorks it so grab the existing legends` line handles and manually update the legend with those handles. This is pretty painful by comparison to the dynamic legend solution above:

% Get object handles
[LEGH,OBJH,OUTH,OUTM] = legend;

% Add object with new handle and new legend string to legend
legend([OUTH;p1],OUTM{:},sprintf('pitch,yaw: %d,%d',pitch,yaw))