MATLAB Answers

Colors on Multi-trace Plots

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Dave on 11 Mar 2013
I've recently encountered a problem I've never seen before. I've read the help documentation, but cannot find the solution.
When you plot multiple curves in a figure, using "plot," for example, MATLAB usually uses different colors for the different curves. But my MATLAB suddenly began to plot all curves blue!
How can I fix this, and avoid it in the future?
Any help would be appreciated.

Answers (1)

Image Analyst
Image Analyst on 11 Mar 2013
Somehow your ColorOrder got messed up. See this demo to see how you can see your current color order and how you can set it to be whatever you want:
% Unless you specify the 'Color' property when you plot,
% plots are plotted according to the 'ColorOrder' property of the axes.
% This demo shows how you can change the default color order of plots.
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
clear; % Erase all existing variables.
workspace; % Make sure the workspace panel is showing.
fontSize = 18;
% Make 20 plots, with 25 data points in each plot.
numberOfDataSets = 20;
x = 1:25;
y = rand(numberOfDataSets, length(x));
% These y would all be on top of each other.
% Separate the plots vertically.
offsets = repmat((1:numberOfDataSets)', [1, length(x)]);
y = y + offsets;
% Get the initial set of default plot colors.
initialColorOrder = get(gca,'ColorOrder') % Initial
% See what the colors look like when plotted:
subplot(2, 1, 1);
plot(x,y, 'LineWidth', 3);
grid on;
caption = sprintf('%d plots with the Initial Default Color Order (Note the repeating colors)', numberOfDataSets);
title(caption, 'FontSize', fontSize);
xlabel('X', 'FontSize', fontSize);
ylabel('Y', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]); % Maximize figure.
% Give a name to the title bar.
set(gcf,'name','Image Analysis Demo','numbertitle','off')
choice = menu('Which ColorOrder do you want?', 'jet', 'random', 'hsv', 'hot', 'cool', 'spring', 'summer',...
'autumn', 'winter', 'lines', 'gray', 'bone', 'copper', 'pink');
% Make a new axes:
subplot(2, 1, 2);
% Create a new colormap that will define the new default color order property.
switch choice
case 1
newDefaultColors = jet(numberOfDataSets);
case 2
newDefaultColors = rand(numberOfDataSets, 3);
case 3
newDefaultColors = hsv(numberOfDataSets);
case 4
newDefaultColors = hot(numberOfDataSets);
case 5
newDefaultColors = cool(numberOfDataSets);
case 6
newDefaultColors = spring(numberOfDataSets);
case 7
newDefaultColors = summer(numberOfDataSets);
case 8
newDefaultColors = autumn(numberOfDataSets);
case 9
newDefaultColors = winter(numberOfDataSets);
case 10
newDefaultColors = lines(numberOfDataSets);
case 11
newDefaultColors = gray(numberOfDataSets);
case 12
newDefaultColors = bone(numberOfDataSets);
case 13
newDefaultColors = copper(numberOfDataSets);
newDefaultColors = pink(numberOfDataSets);
% Note: You can build your own custom order if you want,
% just make up a array with numberOfDataSets rows and 3 columns
% where each element is in the range 0-1.
% Apply the new default colors to the current axes.
set(gca, 'ColorOrder', newDefaultColors, 'NextPlot', 'replacechildren');
% Now get the new set of default plot colors.
% Verify it changed by printing out the new default color set to the command window.
newColorOrder = get(gca,'ColorOrder')
% Now plot the datasets with the changed default colors.
plot(x,y, 'LineWidth', 3);
grid on;
caption = sprintf('%d plots with the New Default Color Order', numberOfDataSets);
title(caption, 'FontSize', fontSize);
xlabel('X', 'FontSize', fontSize);
ylabel('Y', 'FontSize', fontSize);
msgbox('Done with ColorOrder demo!');
Image Analyst
Image Analyst on 12 Mar 2013
That ColorOrder looks fine. The only thing I can think of is you must have an argument to your plot() function that says 'b-', which forces the plots to be blue.

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