Choosing specific line to legend in different matlab runs - matlab

Question

I have made a simulation that calculates trajectories of objects and plot it.
The figure looks like this:
figure(1)
plot(ArrayRT1,ArrayRT2);
hold on
plot(ArrayRD1,ArrayRD2);
plot(ArrayRM1,ArrayRM2);
title('Interception Trajectory')
xlabel('Downrange (Kft)')
ylabel('Altitude (Kft) ')
grid on
Where:
plot(ArrayRT1,ArrayRT2) - 1st object trajectory
plot(ArrayRD1,ArrayRD2) - 2nd object trajectory
plot(ArrayRM1,ArrayRM2) - 3rd object trajectory
Now, I run the same simulation without closing the figure with different initial conditions to check how they affect the trajectories so basically after the 2nd run I will have 6 lines on my graph.
How can I choose when I make legend to show legend only for 4 lines:
1,2,3 from first run and the 6th (the 3rd from the 2nd run)
Thank you.

Answer 1

Option 1
Use the syntax legend(subset,___) to set a legend only to specific objects in you axes. This requires getting the handles to all these objects. You can do that by assigning then to an array of handles, as in the following example:
x = 1:10;
% plotting all the lines:
figure(1)
hold on
p(1) = plot(x,2*x);
p(2) = plot(x,3*x);
p(3) = plot(x,4*x);
p(4) = plot(x,2*x+1);
p(5) = plot(x,3*x+1);
p(6) = plot(x,4*x+1);
hold off
% set the legend to a subset of the lines
legend(p([1:3 6]),{'Line 1', 'Line 2','Line 3','Line 6'})
Alternatively, you can 'tag' the lines to whom you want to attach a legend and use findobj to locate their handles, as done in option 2 below.
Option 2
You can set the property DisplayName for your plots to something like "no legend" (or any other string) and then use a loop to turn it off for these specific plots. Here is an example:
x = 1:10;
% plotting all the lines:
figure(1)
hold on
plot(x,2*x,'DisplayName','Line 1');
plot(x,3*x,'DisplayName','Line 2');
plot(x,4*x,'DisplayName','Line 3');
plot(x,2*x+1,'DisplayName','no legend'); % tag for no legend
plot(x,3*x+1,'DisplayName','no legend');% tag for no legend
plot(x,4*x+1,'DisplayName','Line 6');
hold off
% set the legend off for all lines with 'no legend'
set_leg_off = findobj('DisplayName','no legend');
for k = 1:numel(set_leg_off)
set_leg_off(k).Annotation.LegendInformation.IconDisplayStyle = 'off';
end
% show the legend
legend show
Note that:
You don't need to set the DisplayName for all the lines, only for those you want to remove from the legend. However, if you just write legend show it will ignore them when counting the data lines, so if you omit the DisplayName only for line 6, it will give it the label "data1".
You can use other property like tag to mark the non-legend lines (or any other property that will distinguish between the line you want to plot and those you don't), and then if you decide later to show them they won't appear with the label "no legend". Just remember to correct the findobj call to the property you use.
Keep in mind that changing object's tag or DisplayName does not effect the appearance of them in the legend, this is only a way to mark them for the findobj function, so you can loop only on them and turn the legend off. If you want to turn the legend on later, you need to use this loop again.
In both cases, the result is: