Colorbar with diamond-shape blocks

Hello,

I want to plot a colorbar with customized shapes. When I execute the colorbar command, I get the following colorbar in which each block is rectangular-shaped.

However, I want to plot the colorbar in which each block has a diamond shape as shown in the following eample:

Is it possible to customize the shape of the grid boxes like this?

Any help will be greatly appreciated.

Regards,

AG

[Rik]

Colorbars used to be axes objects. You can take that as an inspiration and create your own replacement for the colorbar that uses a separate axes object and a bunch of calls to patch.

As far as I'm aware (especially in the more modern releases) it is not possible to achieve what you want with a colorbar object.

[Spencer Chen]

I don't think you get that with vanilla Matlab. One way is to create your own colorbar axes and plot 'd' diamond markers.

Blessings,

Spencer

Answer 1

[Adam Danz]

Here are two methods to create a custom legend.

Method 1: Plot dummy variables that only appear in the legend.

plot(nan,nan,'d') will produce a point in the legend but won't appear in the axes.

clf()                
axes()                                    % main axis
hold on                                   % important!
nMarkers = 10;                            % number of markers/colors
labels = 5:5:50;                          % legend labels
colors = jet(nMarkers);                   % Color of each marker (by row)
sh = arrayfun(@(i)scatter(nan,nan,50,colors(i,:),...    % plot invisible markers
    'd','filled','DisplayName',num2str(labels(i))),...
    1:nMarkers);
legend(sh)                                % Specify invisible marker handles

If you'd rather use plot() instead of scatter(),

sh = arrayfun(@(i)plot(nan,nan,'d','Color','none',...
    'MarkerFaceColor',colors(i,:),'DisplayName',...
    num2str(labels(i))),1:nMarkers);

Method 2: Create a pseudo-legend on a separate axes

Produce a 2nd axes and use text() to label points.

clf()
axes('Position',[.1 .1 .7 .7])            % main axes
cbax = axes('position',[.83 .1 .05 .7]);  % color legend axes

nMarkers = 10;                            % number of markers/colors
y = linspace(0.4,1,nMarkers);             % y value of each marker
x = zeros(size(y));                       % x value of each marker
labels = strsplit(strtrim(num2str(5:5:50)));  % "legend" strings
colors = jet(nMarkers);                   % Color of each marker (by row)
scatter(cbax,x,y,50,colors,'d','filled')  % plot the colored diamonds
ylim(cbax,[0,1])                          % Scale the y axis for spacing
text(cbax,x+.4,y,labels,'FontSize',8)     % Add the "legend" strings
axis(cbax,'off')                          % Turn off the legend axis

[Rik]

Neat solution. Although you do need to be careful if you want the diamonds to stay connected. If that is a hard requirement, patch would probably be good solution as well.

[Adam Danz]

I didn't even notice they were connected in the OP's image. Good eye. Another benefit of using patch would be to draw rotated squares rather than diamonds.

[Anindya G]

Excellent solution! I am very grateful!

[Adam Danz]

Thanks! I like method 1 the best, although method 2 gives you more flexibility with spacing etc.