use "set" with trasparent color

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shamal
shamal on 6 Jun 2025
Commented: Walter Roberson on 7 Jun 2025
selected = findobj(allLines,'Type','line','LineWidth',0.5);
set(selected, 'MarkerFaceAlpha',.2,'MarkerEdgeAlpha',.2);
Error using matlab.graphics.chart.primitive.Line/set
Unrecognized property MarkerFaceAlpha for class Line.
Error in mycallback (line 19)
set(selected, 'MarkerFaceAlpha',.2,'MarkerEdgeAlpha',.2);
Error while evaluating Line ButtonDown
Hi, i try to color in trasparente mode but i get error

Accepted Answer

Matt J
Matt J on 7 Jun 2025
Edited: Matt J on 7 Jun 2025
It's undocumented, I believe, but you can control line transparency by setting the Color property to a 4-element RGBA value.
h=plot(rand(5,2),'r', 'LineWidth',4);
set(h(2),'Color',[1,0,0, 0.2]);
  3 Comments
Matt J
Matt J on 7 Jun 2025
Edited: Matt J on 7 Jun 2025
What I gave you in my example does precisely that. Both lines in the plot are red, but the second line has transparency alpha=0.2. That's what a transparent red line looks like (on a white background).
Walter Roberson
Walter Roberson on 7 Jun 2025
Note:
If you serialize a plot (such as save and restore, or send it between parallel workers), then the transparancy set in this manner will be discarded.

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More Answers (1)

Walter Roberson
Walter Roberson on 7 Jun 2025
Line objects have never supported MarkerFaceAlpha or MarkerEdgeAlpha
MarkerFaceAlpha and MarkerEdgeAlpha are used for Scatter plots.
  1 Comment
shamal
shamal on 7 Jun 2025
What do you recommend to make the plotted lines more transparent without changing the color?

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