MATLAB: How to make errorbar transparent

alphaerrorbarMATLABtransparent

How can I make a plot with discrete errorbar points which are transparent?

This thread did not contain an answer: https://www.mathworks.com/matlabcentral/answers/381188-how-to-define-transparency-of-errorbar

Best Answer

Unlike many line plots, the color property cannot be used to set transparency in errorbar().

Transparency can be set from within the hidden Bar and Line objects that represent the errorbars and trend line, respectively.

% Plot errorbars
cla
hold on
plot(rand(20),rand(20)*2-.5, 'yo', 'MarkerFaceColor', 'k', 'MarkerSize', 15, 'LineWidth', 1.5);
h = errorbar(linspace(0,1,5), linspace(0,1,5), .5*ones(1,5), 'r', 'LineWidth', 10);
% Set transparency level (0:1)
alpha = 0.65;   
% Set transparency (undocumented)
set([h.Bar, h.Line], 'ColorType', 'truecoloralpha', 'ColorData', [h.Line.ColorData(1:3); 255*alpha])

Related Solutions

MATLAB: How to make the plot transparent in a gscattter

Setting transparency of markers with gscatter is not possible as of r2020a.

Update: See Yair's method of setting gscatter marker transparency using undocumented features.

Workarounds

You could use scatter() which does support transparency. Here's one way to translate a gscatter syntax to scatter syntax using arrayfun.

% gscatter syntax
gscatter(x,y,g)
% scatter syntax 
cla()
hold on % important

uniqueGroups = unique(group);
h = arrayfun(@(g)scatter(x(group==g), y(group==g), 'filled'), uniqueGroups);
set(h, 'MarkerFaceAlpha', 0.6) % set transparency level

% scatter syntax specifying color, marker, and size
colors = 'rb';
markers = '^v';
uniqueGroups = unique(group);
cla()
hold on % important
h = arrayfun(@(g)scatter(x(group==g), y(group==g), ...
    100, colors(g), 'filled', 'Marker', markers(g)), uniqueGroups);
set(h, 'MarkerFaceAlpha', 0.4, 'MarkerEdgeColor', 'k', 'MarkerEdgeAlpha',  .2) % set transparency level

Alternatively, you could use gscatter without filled markers.

h = gscatter(x,y,g,colors,'os',10);
set(h,'LineWidth',1)

Why transparency in gscatter doesn't work

The scatter function creates scatter objects. Scatter objects have MarkerFaceAlpha and MarkerEdgeAlpha properties that allow you to set transparency levels.

The gscatter function creates line objects. Line objects do not have these properties. Furthermore, an undocumented method of adding transparancy to some graphics objects by adding a 4th element (0:1) to the RGB color definition does not work with gscatter.

MATLAB: How do you control “bar3d” plots transparency and color

To explain the issue, I am using the example found here:

https://www.mathworks.com/help/matlab/ref/bar3.html#bt1bonh

The code to create the bar charts is:

% Close existing plots
close all
load count.dat
Z = count(1:10,:);
% Plot bar graph
figure
b = bar3(Z);
title('Semi-Transparent BarGraph')

After creating the plot you can make the plots transparent by modifying the 'FaceAlpha' property of each group of bar charts in the bar3d object:

% For each surface in bar graph - Loop through
% Set FaceAlpha to 0.3
% Face Alpha controls transparency of surface
% 0 is completely transparent while 1 is opaque
for i = 1:length(b)
  b(i).FaceAlpha = '0.3';
end

In addition, here is further information on changing the colors of the each group of bars individually:

https://www.mathworks.com/matlabcentral/answers/5424-how-to-colorize-individual-bar-in-bar3

Alternatively, you can set a different palette using the "colormap" command:

https://www.mathworks.com/help/matlab/ref/colormap.html

Best Answer

Related Solutions

MATLAB: How to make the plot transparent in a gscattter

MATLAB: How do you control “bar3d” plots transparency and color

Related Question