How can I assign multiple colors to tick labels in plots in MATLAB?

Question

Is it possible to color a single number (or a set of numbers) on one of the axes in MATLAB?

Suppose I have a plot:

plot(1:10, rand(1,10))


        

Answer 1

As an alternative to copying the entire axes contents, it is possible to do this also by creating additional axes objects:

ax = axes();
p = plot(1:10, rand(1,10));
myTick = 3;

% Create new axes with transparent backgrounds
ax2 = axes();
ax3 = axes();
set([ax2 ax3], 'XLim', xlim(ax));
set([ax2 ax3], 'Color', 'none');

set(ax3, 'XTick', [], 'YTick', []);

% Give one new axes a single tick mark
set(ax2, 'YTick', []);
set(ax2, 'XTick', myTick);
set(ax2, 'XColor', 'r');

 % This line is necessary to use the plot toolbar functions like zoom / pan
linkaxes([ax ax2 ax3]);

Answer 2

Single tick labels can be colored using tex markup, which is enabled for tick labels by default. It is defined in the TickLabelInterpreter property of the axis.

It provides two commands for coloring text:

• \color{<name>}, where <name> is a color name like “red” or “green“, and
• \color[rgb]{<R>,<G>,<B>}, where <R>, <G> and <B> are numbers between 0 and 1 and define an RGB color.

These commands can be used to color single tick labels:

plot(1:10, rand(1,10))
ax = gca;

% Simply color an XTickLabel
ax.XTickLabel{3} = ['\color{red}' ax.XTickLabel{3}];

% Use TeX symbols
ax.XTickLabel{4} = '\color{blue} \uparrow';

% Use multiple colors in one XTickLabel
ax.XTickLabel{5} = '\color[rgb]{0,1,0}green\color{orange}?';

% Color YTickLabels with colormap
nColors = numel(ax.YTickLabel);
cm = jet(nColors);
for i = 1:nColors
    ax.YTickLabel{i} = sprintf('\\color[rgb]{%f,%f,%f}%s', ...
        cm(i,:), ax.YTickLabel{i});
end

And this is how the result looks:

The code worked for me in MATLAB R2016b and R2017a.

Answer 3

Unfortunately, you cannot have multiple colors for tick labels in one axes object. However, there's a solution (inspired by this page from MathWorks support site) that achieves the same effect. It overlays the existing axes it with another axes that has only one red tick.

Here's an example:

figure
plot(1:10, rand(1,10))
ax2 = copyobj(gca, gcf);                             %// Create a copy the axes
set(ax2, 'XTick', 3, 'XColor', 'r', 'Color', 'none') %// Keep only one red tick
ax3 = copyobj(gca, gcf);                             %// Create another copy
set(ax3, 'XTick', [], 'Color', 'none')               %// Keep only the gridline

The result is: