Custom colormaps and color bars

Running MATLAB R2013a

I am using a custom colormap created with the colormap command on a plot. When I add a legend, the legend is in the correct color order. However, when I add a colorbar, it uses the 'jet' colormap. How do I get it to use my custom colormap? I included the relevant code below:

%setting the line color order where varycolor is from matlab central

numpowers = 50; %(usually ~20-100)

clrmap = colormap(varycolor(numpowers)); %sets line color order

figure('OuterPosition',[100 100 1000 640],'name',strcat('RLplot',devname),'numbertitle','off');
axes('FontSize',20,'FontName','Times New Roman','ColorOrder',clrmap);

grid on; 

hold all;

box on; 

for i = 1:length(structkey) 

    %each structure element in the structure contains a dataset
    %a new color is assigned for each structure element
    %each structure element corresponds to a number, say 1:1:50
    eval(['RL = RLdata.' char(structkey(i)) ';']);
    L=RL(:,1);  %#ok<NODEF>
    R=RL(:,2); 

    % Least squared linear fit to data
    x=0:3:24;
    fitcoeff = polyfit(L,R,1);
    fiteqn = polyval(fitcoeff,x);

    %Plot data
    plot(L,R,'x',x,fiteqn,'-','Color',clrmap(i,:),'LineWidth',1.5);

    %Write the string that will become the legend --> how I did the legend
    %    tmplgd = char(structkey(i));
    %    tmplgd = str2double(tmplgd(2:end-2))/1000;

    %    legendstr(2*i-1,1) = cellstr(sprintf('%0.3f %s', tmplgd, '\muW/\mum^3')); %#ok<AGROW>
    %    legendstr(2*i,1) = cellstr(sprintf('%s %0.1f %s %0.1f', 'y =', ...
    %         fitcoeff(1,1), 'x +', fitcoeff(1,2))); %#ok<AGROW>

end

Answer 1

[Kelly Kearney]

When trying to match colors of lines for objects plotted one at a time in a loop, I usually find it easier to manually set line colors, rather than trying to rely on the color order of the axis. For the record, your example does this; even though you set a color order you never actually use it, since you override the defaults with your specific colors. Keep in mind that the colormap (of a figure) and color order (of an axis) are two different things, and need to be set separately.

cmap = jet(5);

figure;
hold on;
for ii = 1:5
  y = rand(10,1);
  h(ii,1) = plot(1:10, y, 'color', cmap(ii,:));
  h(ii,2) = plot(1:10, y+0.1, 'color', cmap(ii,:), 'linestyle', '--');
end
legend(h(:,1), {'one', 'two', 'three','four','five'});
colormap(cmap);
colorbar;

[Becca]

I changed my cmap array so that I do not need to call it in the plot command. This did not fix it. However, when I moved the colormap(cmap) command from before the plot (and axes call) to just befor the colorbar as in your example, it worked.

Thank you

Answer 2

[Andrew Newell]

With the command

clrmap = colormap(...)

you only define the variable clrmap, not set the colormap. Here is a simple example of how you could make colormap work:

clrmap = colormap(lines); %sets line color order
colormap(clrmap);
figure
axes('ColorOrder',clrmap);
hold all;

for i = 1:5
  plot(0:1,[0 i])
end
colorbar

Note that, having defined the color order, you don't need to refer to it explicitly in the plot.

[Becca]

I tried this and it still didn't work. Maybe it is a technicality with the way I plotted?

I include the color in the plot command because I want both plots created in the call to have the same color. That is, the data and the fit line are the same color. If I don't include the color, it doesn't work. I guess I could somehow write this into the colormap and that might fix the problem. Is there a different plot command (ie - fplot) that would achieve the same thing (data & fit plot the same color in each iteration)?

[Andrew Newell]

Did my example work without change? It should have both the lines and the colorbar using colormap lines, which has rapid changes in color. You could try substituting your colormap. Explicitly including the color in the plot commands is a side issue.

[Becca]

Your example did work, but I could not get it to apply directly. I did get it to work in my program by moving the "colormap(clrmap);" command to just before the "colorbar" command.

Thank you