How to show legend for only a specific subset of curves in the plotting?

Question

t = 0 : 0.01 : 2 * pi;
s = sin(t);
c = cos(t);
m = -sin(t);

hold on;
plot(t, s, \'r\');
plot(t, c, \'b\');
plot(t, m, \'g\');
hold off;

legend(\'\', \'cosine\', \'         


        

Answer 1

Let's start with your variables and plot them:

t = 0 : 0.01 : 2 * pi;
s = sin(t);
c = cos(t);
m = -sin(t);

figure;
hold ('all');
hs = plot(t, s);
hc = plot(t, c);
hm = plot(t, m);

There is a property called IconDisplayStyle. It is buried quite deep. The path you need to follow is:

Line -> Annotation -> LegendInformation -> IconDisplayStyle

Setting the IconDisplayStyle property off will let you skip that line. As an example, I am going to turn off hs's legend.

hsAnno = get(hs, 'Annotation');
hsLegend = get(hsAnno, 'LegendInformation');
set(hsLegend, 'IconDisplayStyle', 'off');

Of course you can go ahead and do it like this:

set(get(get(hs, 'Annotation'), 'LegendInformation'), 'IconDisplayStyle', 'off');

But I find it much harder to understand.

Now, the legend function will just skip hs.

Ending my code with this:

legend('cosine', 'repeat for this handle')

will give you this:

EDIT: Jonas had a nice suggestion in the comments: Setting the DisplayName property of hc like this:

set(hc, 'DisplayName', 'cosine');
legend(gca, 'show');

will give you the legend you need. You will have associated your line handle with 'cosine'. So, you can just call the legend with 'off' or 'show' parameters.