# How to add a legend for a plot generated with a function multiple times?

2 vues (au cours des 30 derniers jours)
Niccolò Bruno le 14 Avr 2023
Commenté : Niccolò Bruno le 14 Avr 2023
I am working with orbits around Earth. To plot them, I use a function with the orbital parameters as input. My problem is that I don't know how to create a legend when calling the function more than one time to show on the same plot multiple orbits.
Adding a legend manually like this
plotOrbit(a, e, i, OM, om, th0, thf, dt, mu)
plotOrbit(a1, e1, i1, OM1, om1, th0, thf, dt, mu)
legend("Initial orbit", "Final orbit")
give me a wrong line for the second orbit. (It should be orange instead of a random blue tiny line). I tried to follow a different approach
txt = 'Initial orbit';
plotOrbit(a, e, i, OM, om, th0, thf, dt, mu, txt)
txt = 'Final orbit';
plotOrbit(a1, e1, i1, OM1, om1, th0, thf, dt, mu, txt)
legend show
Adding this line in the function script
plot3(r(1, :), r(2, :), r(3, :), 'DisplayName',txt, LineWidth=2)
Now the legend shows the right lines, but the result shows 4 extra labels that I don't know how to remove. ù
Do you know how to solve this? Thank you
##### 2 commentairesAfficher AucuneMasquer Aucune
Steven Lord le 14 Avr 2023
It's going to be difficult to offer any specific suggestions without seeing what your plotOrbit function is doing.
Niccolò Bruno le 14 Avr 2023
Even if @Antoni Garcia-Herreros helped me already, I add the function for completeness.
function plotOrbit(a, e, i, OM, om, th0, thf, dt, mu)
r = [];
for t = th0:dt:thf
r = [r, parorb2rv(a, e, i, OM, om, t, mu)];
end
% this gives the position in a cartesian frame in the form r = [x; y; z]
figure(1)
plot3(r(1, :), r(2, :), r(3, :), LineWidth=2)
axis equal; % Make the axes scales match
title("Orbits");
hold on; % Add to the plot
Terra3d %function to add the 3d model of the Earth
end

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### Réponse acceptée

Antoni Garcia-Herreros le 14 Avr 2023
Modifié(e) : Antoni Garcia-Herreros le 14 Avr 2023
Hello,
As @Steven Lord pointed out it's hard to suggest anything without knowing how plotOrbit works, but you could try something like this:
plotOrbit(a, e, i, OM, om, th0, thf, dt, mu)
plotOrbit(a1, e1, i1, OM1, om1, th0, thf, dt, mu)
l=legend('Initial orbit','','','Final orbit');
##### 1 commentaireAfficher -1 commentaires plus anciensMasquer -1 commentaires plus anciens
Niccolò Bruno le 14 Avr 2023
Thank you! This works perfectly

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