MATLAB: How to change the appearance of the lines in the legend in a MATLAB figure

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I want to alter the appearance of the lines in the legend in my MATLAB figure. For example, the markers are too small and difficult to see. I would like to make them larger.

Best Answer

The handles for the line objects in the legend are returned as part of the output from LEGEND. You can use the SET command to change the properties if you have the lines' handles:

x = 1:10;
y1 = rand(1,10); % 10 random numbers 
y2 = randn(1,10); % 10 normally distributed random numbers 
plot(x,y1,'rx--',x,y2,'bo-')
[legh,objh] = legend('curve1','curve2'); % handles to the legend and its objects

There would be two line objects each (4 in total) associated to each of the line objects in the original plot.This can be found by:

% find the handles in 'objh' that correspond to line objects
lineh = findobj(objh,'type','line')

Two are used to display the lines' LineStyle with their Marker property set to 'none'. The other two are used to display the same markers as the lines in the plot with their linestyles set to 'none'. Setting the MarkerSize will only affect the appearance of the lines that have markers.

% set the marker size
set(lineh,'MarkerSize',10)

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MATLAB: Lenend keep only text

dummyh = line(nan, nan, 'Linestyle', 'none', 'Marker', 'none', 'Color', 'none');
dummyv = line(nan, nan, 'Linestyle', 'none', 'Marker', 'none', 'Color', 'none');
dummyz = line(nan, nan, 'Linestyle', 'none', 'Marker', 'none', 'Color', 'none');
legend([dummyh dummyv dummyz],{'\color{red}one','\color{green}two','\color{blue}three'})

MATLAB: How to place a legend on a plot produced from the PLOTYY command in MATLAB 7.5 (R2007b)

This enhancement has been incorporated in Release 2008a (R2008a). For previous product releases, read below for possible workarounds:

The PLOTYY command creates two axes. In the first axes it plots the first (x1,y1) data set and in the second axes it plots the second (x2,y2) data set.

With the code above, two axes are created and two lines are plotted. The first axes has a white color and the second axes has a color of 'none'. This allows you to see the line drawn in the first axes. When the LEGEND command is executed it obtains the line information from the current axes which contains only one line. Therefore, the resulting legend only shows one line.

To create a plotyy figure with a legend, try the following:

% Create the plotyy figure.  The handle to the first line is h1 and the handle 
% to the second line is h2.
x = 1:10;
y = 10:-1:1;
[ax,h1,h2] = plotyy(x,x,x,y);
% Make the second axes current (the axes with a color of 'none') so that both lines 
% are visible
axes(ax(2))
%Create the legend and explicitly state the handles to each line
[legh, objh] = legend([h1 h2],'str1', 'str2');

Best Answer

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MATLAB: Lenend keep only text

MATLAB: How to place a legend on a plot produced from the PLOTYY command in MATLAB 7.5 (R2007b)

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