Matlab - how to make a custom legend

Question

I have the following picture :

And I would like to make a legend for it. Basically, I want to make a legend for each type of rectangle. In the legend box, I want to mark each color line according to the type of body which it marks:

• green line : head
• yellow line : torso
• purple line : right arm
• cyan line : left arm
• red line : left leg
• blue line : right leg

This is basically custom, because I have more rectangles of each type. How can I do a custom legend and attach it to the figure which draws this picture?

Answer 1

I would like to add to dvreed77's answer on using hggroup that for clean legend use, I also needed to set the 'IconDisplayStyle' (Matlab R2014a), such that:

%4 kinds of lines:
n_areas = 4;
n_lines = 10;

%use built-in color map
cmap = hsv(n_areas);

%plot lines and generate handle vectors
h_fig = figure;
hold on
h_lines = zeros(1,n_lines);

for l = 1:n_areas

  for k = 1:n_lines
    h_lines(k) = plot(rand(1,2), rand(1,2),'Color',cmap(l,:));
  end

  %Create hggroup and set 'icondistplaystyle' to on for legend
  curPlotSet = hggroup;
  set(h_lines,'Parent',curPlotSet);
  set(get(get(curPlotSet,'Annotation'),'LegendInformation'),...
      'IconDisplayStyle','on');
end

%Now manually define legend label
legend('heads','legs','hands','feet')

Answer 2

There are 2 ways you could go about this. You could create your squares and then assign them to an hggroup. This way you dont have multiple items for each color. Something like this:

hold on
for ii = 1:4
    hb(ii) = plot(rand(1,2), rand(1,2),'color','r'); 
end

hg = hggroup;
set(hb,'Parent',hg) 
set(hg,'Displayname','Legs')

legend(hg)

Or you could create dummy objects, like this:

hold on
for ii = 1:4
    hb(ii) = plot(rand(1,2), rand(1,2),'color','r'); 
end

p = plot([],[],'r');

legend(p,'Legs')

The former is a little more elegant.