Breaking legend into several parts and moving parts as necessary to prevent overlapping graphed data.

How do I automatically check to see if the legend is covering plotted data.If the legend isn't covering any data than do nothing. Otherwise, break up the legand and start placing las much egend information as possible in the northest, then northwest, then southwest, and finally in the southeast.

fig=figure('Name',['dq0 variables: powers & load torque = ' loadtorque ' (N∙m)']);
fig.Position = [300 300 360 220];  % [left, bottom, width, height]
hold on;
plot(pin_dq0/1000);
plot(pqd0s_dq0/1000);
plot(pqd0r_dq0/1000);
plot(pshaft_dq0/1000);
hold off;
title('');
ylim([-75 225])
yticks(-50:50:250);
xlabel('Time (s)',Fontname='Times New Roman',fontsize=8);
ylabel('Power (kW)',Fontname='Times New Roman',fontsize=8);
legend('P_{in} apparent' , ...
    'P_{stator} losses', ...
    'P_{rotor} losses referred', ...  
    'P_{shaft}', ...
    fontname='Times New Roman',fontsize=8);
box off;
grid on;

Answer 1

[Star Strider]

I doubt that it is possible to break up the legend or have more than one legend in an axes object.

There are a few options you could pursue:

One could be:

lgd = legend ( ... )

lgd.NumColumns = 2;

lgd.Location = 'northoutside';

Another could be:

legend( ..., Location='eastoutside')

And other variations.

See the legend documentation for details.

EDIT — (29 Apr 2025 at 19:44)

Here is another option, using annotation objects —

Fs = 1000;
L = 2;
t = linspace(0, Fs*L, Fs*L+1).'/Fs;
PkW = sin(t*(10:10:40)*2*pi) + 1+(0:3)*4;

figure
plot(t, PkW)
grid
xl = xlim;
yl = ylim;
Ax = gca;
Ax.OuterPosition = Ax.OuterPosition .* [0.9 1 0.85 1];
pos = Ax.InnerPosition;

xapf = @(x,pos,xl) pos(3)*(x-min(xl))/diff(xl)+pos(1);                % 'x' Annotation Position Function
yapf = @(y,pos,yl) pos(4)*(y-min(yl))/diff(yl)+pos(2);                % 'y' Annotation Position Function

endvals = PkW(end,:);

for k = 1:size(PkW,2)
    annotation('arrow', xapf([2.2 2], pos,xl), yapf([1 1]*endvals(k),pos,yl))
    % Q = [k xapf(2.2,pos,xl), yapf(endvals(k)-0.5,pos,yl), xapf(0.5,pos,xl), yapf(1,pos,yl)]
    annotation('textbox', [xapf(2.2,pos,xl), yapf(endvals(k)-2.35,pos,yl), xapf(0.5,pos,xl), yapf(1,pos,yl)], 'String',sprintf('Column %d',k), 'FitBoxToText',1)
end

If I had your data, I could probably write specific code for it using this approach. (I wrote the 'xapf' and 'yapf' functions myself to make the absolute reference calculations easier.) You can probably also use text objects for this.

Answer 2

[Thorsten]

You can check if the legend covers plotted data using the function proposed here: https://de.mathworks.com/matlabcentral/answers/448649-how-to-place-a-legend-in-best-corner

If there is a clash I would increase the y-axis and replot the legend such that the legend does not overlap the data.