How do I add a key to my plot?

My plot has four variables in it (x1,y1,x2,y2) representing two EN coordinates. How do I add a key to show which is which?

Also, it would be useful if I could ensure the x and y had the same scale (but not a fixed scale).

[DGM]

You mean legend()?

For the second part, can you use axis equal or axis square? If not, you'll need to clarify what you want.

Answer 1

[Voss]

To add a key showing which line is which, you can use legend().

To ensure the same x- and y-scale, you can use axis equal.

figure();

% random data with different y-scales
line_x1 = plot(randn(1,10),4*randn(1,10));
hold on
line_y1 = plot(randn(1,10),3*randn(1,10));
line_x2 = plot(randn(1,10),2*randn(1,10));
line_y2 = plot(randn(1,10),randn(1,10));

% equal x- and y-scale
axis equal

% make a line key (a.k.a. legend)
names = {'x1','y1','x2','y2'};
legend([line_x1 line_y1 line_x2 line_y2],names);

[John]

Great answer. I often need to use underscores in my plot titles and legends. So had that been the case here, you can add ,'Interpreter', 'none' to the legend:

figure();
% random data with different y-scales
line_x1 = plot(randn(1,10),4*randn(1,10));
hold on
line_y1 = plot(randn(1,10),3*randn(1,10));
line_x2 = plot(randn(1,10),2*randn(1,10));
line_y2 = plot(randn(1,10),randn(1,10));
% equal x- and y-scale
axis equal
% make a line key (a.k.a. legend)
names = {'line_x1','line_y1','line_x2','line_y2'};
legend([line_x1 line_y1 line_x2 line_y2],names,'Interpreter', 'none');

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