MATLAB Colorbar - Same Colors, Scaled Values
Consider the following example:
[ X, Y, Z ] = peaks( 30 );
figure( 100 );
surfc( X, Y, Z );
zlabel( 'Absolute Values' );
colormap jet;
c = colorbar( 'Location', 'EastOutside' );
ylabel( c, 'Relative Values' );
The output looks like this:
How can I scale ticks on a color bar i.e. scale the c axis (for example, divide values by 100):
- without changing z values and colors on the graph
- without changing colors on the color bar
- without changing the relationship between the colors in the plot, the colors in the color bar, and the z-values of the plot
- when using the full range of the color scale
In the picture above, I would like to scale the c-axis so that it shows these values for the corresponding z:
z | c-axis
----------
8 | 8/100
6 | 6/100
4 | 4/100
. | ...
The function caxis
, as I understand it, is not suitable here, since it will simply show the colors for the subsection of the z-axis, and not for the entire z-axis.
Bonus question: how can the color display and color bar be scaled as a function of X, Y and / or Z?
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[ X, Y, Z ] = peaks( 30 );
figure( 101 );
surfc( X, Y, Z );
zlabel( 'Absolute Values' );
%
Z_Scl = 0.01;
Z_Bar = linspace( min(Z(:)), max(Z(:)), 10 );
%
colormap jet;
c = colorbar( 'Location', 'EastOutside', ...
'Ticks', Z_Bar, 'TickLabels', cellstr( num2str( Z_Bar(:)*Z_Scl, '%.3e' ) ) );
ylabel( c, 'Relative Values' );
For arbitrary mapping between z values and a color bar can be combined surf
, contourf
and contour
as follows (inspired by these two excellent answers):
[ X, Y, Z ] = peaks( 30 ); % Generate data
CB_Z = (sin( Z/max(Z(:)) ) - cos( Z/max(Z(:)) )).^2 + X/5 - Y/7; % Generate colormap
CF_Z = min( Z(:) ); % Calculate offset for filled contour plot
CR_Z = max( Z(:) ); % Calculate offset for contour plot
%
figure( 102 ); % Create figure
clf( 102 );
hold on; grid on; grid minor; % Retain current plot and create grid
xlabel( 'x' ); % Create label for x-axis
ylabel( 'y' ); % Create label for y-axis
zlabel( 'Scaling 1' ); % Create label for z-axis
surf( X, Y, Z, CB_Z ); % Create surface plot
%
CF_H = hgtransform( 'Parent', gca ); % /questions/901054/plot-multiple-2d-contour-plots-in-one-3d-figure-matlab/3212833#3212833
contourf( X, Y, CB_Z, 20, 'Parent', CF_H ); % Create filled contour plot
set( CF_H, 'Matrix', makehgtform( 'translate', [ 0, 0, CF_Z ] ) ); % /questions/901054/plot-multiple-2d-contour-plots-in-one-3d-figure-matlab/3212833#3212833
%
CR_H = hgtransform( 'Parent', gca ); % /questions/901054/plot-multiple-2d-contour-plots-in-one-3d-figure-matlab/3212833#3212833
contour( X, Y, CB_Z, 20, 'Parent', CR_H ); % Create contour plot
set( CR_H, 'Matrix', makehgtform( 'translate', [ 0, 0, CR_Z ] ) ); % /questions/901054/plot-multiple-2d-contour-plots-in-one-3d-figure-matlab/3212833#3212833
%
colormap jet; % Set current colormap
CB_H = colorbar( 'Location', 'EastOutside' ); % Create colorbar
caxis( [ min( CB_Z(:) ), max( CB_Z(:) ) ] ); % Set the color limits for the colorbar
ylabel( CB_H, 'Scaling 2' ); % Create label for colorbar
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As I wrote in your answer , I believe that the best choice for displaying two related values is not to create a new axis for that, but to show them side by side with the other. Here's a suggestion:
[X,Y,Z] = peaks(30);
surfc(X,Y,Z);
zlabel('Absolute (Relative) Values');
colormap jet
Z_Scl = 0.01;
zticks = get(gca,'ZTick');
set(gca,'ZTickLabel',sprintf('%g (%g)\n',[zticks;zticks.*Z_Scl]))
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