Colormap won't change

Colormap no longer changes the colour map used by a plot?

I declare some new colours:

   cols = [0.60 0.86 0.91;   % skyblue
           0.90 0.96 0.94;   % paleblue
           0.82 0.71 0.48;   % palebrown
           0.87 0.42 0.41;   % pink
           0.97 0.65 0.52;   % palepink
           0.98 0.84 0.66;   % sand
           0.58 0.74 0.81;   % midblue
           0.60 0.86 0.72;   % steel
           1.00 0.97 0.50;   % paleyellow
           0.80 0.89 0.25;   % lime
           0.30 0.75 0.59;   % turquoise
           0.70 0.71 0.27;   % olive
           0.50 0.80 0.32;   % palegreen
           0.98 0.78 0.20;   % mustard
           0.70 0.57 0.46];  % chocolate

Then I construct my data array (multiple series)

Then I open a figure, and set the colormap to my colours.

Then I create axes, and again set their colormap to my colours.

I plot my series, and again set the colormap (both syntaxes this time).

Finally a legend, with - yes! - another colormap call.

f1 = figure;
orient landscape;
colormap(f1,cols)
ax = axes('Position',[0.1,0.1,0.8,0.8],'Box','on');
colormap(ax,cols)
plot(xvy,dy,'LineWidth',1);
colormap(ax,cols)
colormap(cols)
legend(labs,'Location','southwest')
colormap(ax, cols)

It still just displays seven Parula colours and recycles them for my remaining series (I have ten).

Obviously I've tried colormap calls everywhere separately as well.

Thanks for any obvious error spotting!

Harry

[Stephen23]

"...It still just displays seven Parula colours..."

I doubt that. Unless someone set the default ColorOrder to parula.

Answer 1

[Stephen23]

You are plotting lines using plot, which determines the line color using the axes ColorOrder property. This is explained in the plot documentation: " plot uses colors and line styles based on the ColorOrder and LineStyleOrder properties of the axes."

So line color has absolutely nothing to do with the colormap, and has absolutely nothing to do with parula: the color of lines is defined by the axes ColorOrder property. You might like to look at the line colors: do you see all of those colors in parula? Where?

You can search for "MATLAB Line ColorOrder" and find plenty of help:

https://www.mathworks.com/help/matlab/graphics_transition/why-are-plot-lines-different-colors.html

https://www.mathworks.com/help/matlab/creating_plots/defining-the-color-of-lines-for-plotting.html

If you want simple working examples of how to set the line ColorOrder, then have a look at the examples of one of my FEX submissions, e.g.:

https://www.mathworks.com/matlabcentral/fileexchange/45208-colorbrewer--attractive-and-distinctive-colormaps

Otherwise you can simply explicitly define the color when calling plot, or by setting the line color property once the lines have been created. Whatever works for you.

[Ian Harris]

Thank you, that answered my question.

I would describe the solution as, 'non-intuitive'; that is, it is only obvious once you know it.

[Stephen23]

@Ian Harris: it is worth understanding that the colormap and line ColorOrder have two very different goals: colormaps are almost always used to indicate the relationship between data values, i.e. to show how similar or different data values are. As such the colors actually represent data. In contrast the ColorOrder simply distinguishes different lines, and the colors do not represent data. The main goals are to be distinguishable and aesthetically attractive. It is surprisingly difficult to generate distinguishable but attractive colors, and thus most plotting software use some hand-picked set of colors.

"Thank you, that answered my question."

I hope that it helps. Remember to accept the answer that helps you most to resolve your question. Accepting answers is the easiest way for you to show you appreciation to the volunteers who come here and help you.

Answer 2

[Image Analyst]

See my attached colororder demos

[Ian Harris]

Thank you!