MATLAB: Does the legend display lines that look different when using the “stairs” function as opposed to using “plot” in MATLAB R2016b on Linux

MATLAB

In MATLAB R2016b, I'm trying to use the subplot command to generate 2 different plots. One plot using the "stairs" function and one plot using the "plot" function. When adding legends to both plots, the legend for the "stairs" plot seems to render poorly. The line on the legend corresponding to the second line plotted seems to be a slightly different color and line thickness than the line on the plot itself.

Best Answer

It seems the underlying issue is that "stair" plots use "AlginVertexCenters" on its "LineStrip" primitive, which creates crisper and slightly darker lines. The legend icons do not use "AlignVertexCenters" because doing so would create a color inconsistency for most plots.

The workaround for this particular case is to turn off "AlignVertexCenters" on the stair plot.

For example,

s=stairs(1:10);

s.Edge.AlignVertexCenters = 'off';

Note: This is undocumented functionality and is therefore subject to change at any time.

Another potential workaround is to render graphics using "software opengl" instead of "hardware opengl".

In order to switch to software opengl in Linux, you will need to start MATLAB with the -softwareopengl flag set. The following is how it would look in the terminal:

matlab -softwareopengl

To set your preferences so that MATLAB always starts with software opengl on this computer, execute this command at the MATLAB command line:

>> opengl('save','software')

Related Solutions

MATLAB: Do I get an error when setting the LineStyle property for multiple lines in MATLAB 7.4 (R2007a)

The "LineStyle" property for a line object only accepts values of '-', '--', ':', '-.' or 'none'. You can use the "Marker" property to separately set marker symbols. To illustrate, here is an example:

h = plot(rand(10,6))
set(h, {'LineStyle'}, {'-';'--';'--';':';':';':'})
set(h, {'Marker'}, { 'none'; 'o'; 'x'; 'none'; 'none'; 'none'; })

For further help with Line properties in R2007a, refer to the corresponding documentation:

https://www.mathworks.com/help/releases/R2007a/techdoc/index.html?/help/releases/R2007a/techdoc/ref/line_props.html

For your reference, here is a link to the corresponding documentation for a more recent MATLAB version, e.g. R2018b:

https://www.mathworks.com/help/releases/R2018b/matlab/ref/matlab.graphics.chart.primitive.line-properties.html

MATLAB: How to create a legend with multiple outputs

The recommended workflow for creating a legend entry that does not match an existing plot in your data is to create a separate entry in your plot with either empty or NaN data. This will render the new entry invisible, but it will still show up in the legend. Then you can adjust the properties of that new object to make the legend entry appear as you require.

Below is the example on how you can do it. Please run the below code in command line and also in App Designer.

hFig = figure;
hAx = axes(hFig);
hScatter= scatter(hAx,1:10,1:10,'b');
hold on;
hObj(1)=plot(NaN,'b','Marker','o','LineWidth',2,'MarkerEdgeColor','k','MarkerFaceColor','b','LineStyle','none','MarkerSize',10);
hObj(2)=plot(NaN,'b','Marker','o','LineWidth',2,'MarkerEdgeColor','k','MarkerFaceColor','b','LineStyle','none','MarkerSize',12);
lg=legend(hObj,{'My Data 1','My Data 2'});

Best Answer

Related Solutions

MATLAB: Do I get an error when setting the LineStyle property for multiple lines in MATLAB 7.4 (R2007a)

MATLAB: How to create a legend with multiple outputs

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