MATLAB: Scatter 2D plot with specific colorbar

colorbarscatter

I have three coloumn vectors x, y and z. I have made a scatter plot of x and y with z representing the number of occurrence of 'y' in different colours. See the fig. 1 attached.

Now I need a specific colorbar as shown in fig. 2.

Can anyone help me with the codes in R2014a Matlab.

Best Answer

You can try something like this:

imagesc % Just to get something to show
axP = get(gca,'position');
% Create axes for colorbar
axCB = axes('position',[axP(1)+axP(3)+ 0.005 axP(2),0.03 axP(4)]);
X = logspace(0,log10(2^11),101)';
pcolor([1 2],X,log10([X,X]))
set(gca,'yscale','log')
shading flat
set(gca,...
    'yaxisLocation','right','ytick',[1:9,10:10:90,100:100:1000 2048],...
    'yticklabel',{'1','','','','','','','','',...
                 '10','','','','','','','','',...
                 '100','','','','','','','','',...
                 '1000','2048'},...
    'tickdir','out',...
    'box','off',...
    'xtick',[])

You might have to doodle a bit with the position of the main axes and the colorbar-axes to get the best layout for your case, and select a suitable colormap.

HTH

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You can do that task by setting CLim of the axes, like:

figure
imagesc(rand(4));
ax = gca;
ax.CLim = [0 1];
colorbar

MATLAB: How do i create a colour quiver plot (colquiver) on top of a pcolor depth map

"How can I ... use 2 colourmaps and have 2 colourbars?"

An axis can have more than 1 colorbar but it cannot have more than 1 colormap. A simple solution is to create a second, invisible axes for the sole purpose of hosting a second colormap while all of your data are plotted on the main, visible axis.

Here's a demo (see inline comments for details). I'm using the quiver function instead of the 3rd party colquiver function you mentioned.

% Add primary axes and assign a colormap for the pcolor data
figure()
ax = axes(); 
ax.Colormap = bone(255); 
hold on
% Plot the pcolor data
[X,Y] = meshgrid(-2:0.2:2);
Z = X .* exp(-X.^2 - Y.^2);
h = pcolor(X,Y,Z);
h.EdgeColor = 'none';
% Add a 2nd invisible axis to host the 2nd colormap and colorbar
% HandleVisibility is set to off to avoid accidentally accessing those axes.
ax2 = axes('Visible','off','HandleVisibility','off'); 
% Define the colormap for the quiver data
cmap = hot(size(Z,1)); 
ax2.Colormap = cmap; 
% Plot the quiver data
[U,V] = gradient(Z,0.2,0.2);
for i = 1:size(Z,1)
    quiver(X(i,:),Y(i,:),U(i,:),V(i,:), .2, 'Color', cmap(i,:), 'LineWidth',2)
end
% Set properties for the main axes
axis equal
xlim([-2,2])
ylim([-2,2])
% Add the two colorbars and position the main axes so that
% both colorbars fit on the right side. 
cb(1) = colorbar(ax); 
axPos = ax.OuterPosition; 
cb(2) = colorbar(ax2); 
% Split the vertical space between the 2 CBs.
cb(2).Position(4) = cb(2).Position(4)*.48;
cb(1).Position(4) = cb(1).Position(4)*.48;
cb(1).Position(2) = sum(cb(2).Position([2,4]))+.04; 
cb(2).Position([1,3]) = cb(1).Position([1,3]); 
ax.OuterPosition = axPos; 
% Set colorbar range
caxis(ax2, [-4,4])
% Label the colorbars
ylabel(cb(1),'pcolor')
ylabel(cb(2),'quiver')

Best Answer

Related Solutions

MATLAB: How to change color bar limits in imagesc

MATLAB: How do i create a colour quiver plot (colquiver) on top of a pcolor depth map

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