if else in for loop+looping through line colors for plot

I'm reading a set of files and setting my plotting characteristics. When I get to a certain number of variables, 15 in this case I run out of regular RGB colors, other than yellow and black. I am using another variable later on in my script as black and yellow is just hard to see. I'm trying to add in additional colors in my loop but I get the index exceeds matrix dimensions error.

This is due to the fact that i is at 16, but I only have 15 total additional Line styles and 5 additional colors. How do I get it to continue going through the files but just start at the beginning of the other LineStyles and extraLineColor variables to continue plotting other lines styles/colors?

Here's my code:

    % % %load in files
    [files]= dir('*.median.stat');

    % %Set plotting characteristics
    lWidth = 2;
    extraLineColors={rgb('orange') rgb('purple') rgb('DarkGray') rgb('Pink') rgb('Brown')};
    LineStyles = {'--' ':' '-' '--' ':' '-' '--' ':' '-' '--' ':' '-' '--' ':' '-'};
    stationLineStyles = {'r--' 'r:' 'r-' 'b--' 'b:' 'b-' 'g--' 'g:' 'g-' 'm--' 'm:' 'm-' 'c--' 'c:' 'c-'};
    labelSize = 14;
    titleSize = 16;
    if (i <= 15)
    semilogx(files(i).data(:,1),files(i).data(:,2), stationLineStyles{i},'LineWidth',lWidth)
    hold on 
    else (i > 15)    semilogx(files(i).data(:,1),files(i).data(:,2),'LineStyle',LineStyles{i},'Color',
extraLineColors{i},'LineWidth',lWidth)
    legendn{i} = [sta ' ' loc ' ' chan];   
    end
  end

I know I am probably doing something really silly here or am just tired. Can anyone clue me into to what I'm doing wrong?

Answer 1

[Image Analyst]

Try using a predefined colormap like jet.

myColorMap = jet(length(files)); % One unique color for each file.

Then, to use this colormap for the ith line, do this:

semilogx(files(i).data(:,1),files(i).data(:,2),...
   'LineStyle',LineStyles{i}, ...
   'Color',myColorMap(i,:),...
   'LineWidth',lWidth)

[Katherine]

This is close to what I want, but I want every 3 files to have the same color just a different LineStyle, i.e., '--',':','-' because they go together (hence the stationLineStyles definition). Also with this option then then legend:

    legendn{i} = [sta ' ' loc ' ' chan];

doesn't represent the right colors. Is there an easy way to make jet group by 3's?

[Katherine]

Actually I mispoke. The legend is fine and represents what the colors are. But the colors are too close to one another, it's difficult to differentiate them on the plot.

[Image Analyst]

Try colormaps other than jet, like hsv or winter, etc.

[Katherine]

Yep, I looked into the other colormaps and found hsv, but it still would need to grade every 3 files so that 3 files match the same color and then it moves on.

[Image Analyst]

I'm not sure I understand what you said, but you can create your own custom colormap with whatever colors you want. Or you can use

myColorMap = rand(length(files), 3);

to create one with random colors.

[Katherine]

I guess I meant that I would like the color to change every 3 files if possible, and to have the colors that follow by distinctly different from the others so I can distinguish them on the plot.

[Image Analyst]

You could just pick random colors that are different than each other. Expand out by 3 to have every three curves be the same color (let me know if you can't figure out how to do that):

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; 

% Make up a different colormap for each line
cm = rand(numberOfDataSets,3); % Initialize with random color.
% Replicate it 3 times
% cm = repmat(cm, [3, 1])
for p = 2 : numberOfDataSets
  nextColor = rand(1,3); % Random color.
  % Make sure it's not too bright (close to white).
  if sum(nextColor) > 0.8*3
    % It's too bright, pick another color.
    continue;
  end
  % Make sure it's different than the last color by some amount
  priorColor = cm(p-1,:);
  distance = sqrt((priorColor(1) - nextColor(1))^2 + ...
    (priorColor(2) - nextColor(2))^2 + ...
    (priorColor(3)- nextColor(3))^2);
  if distance > 0.3 % or whatever
    cm(p, :) = nextColor;
  end
end

% Now plot the curves.
for p = 1 : numberOfDataSets
  thisColor = cm(p, :)
  plot(x,y(p,:), 'Color', thisColor,'LineWidth', 3);
  hold on;
end
  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')

msgbox('Done with demo!');

[Image Analyst]

If you want colors that are all different from each other by at least some specified amount, you can use this code:

% Script to pick widely different colors in RGB space and plot a curve with each one.
% Colors are guaranteed to have a color difference (in RGB space) of at least 0.1 (25.5 gray levels).
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;

minColorSeparation = 0.1; % In RGB space.  Colors will be no closer than this to each other.
r = 0 : minColorSeparation : 1;
g = r;
b = r;
% Make a 3D grid of all color coordinates possible.
[rr, gg, bb] = meshgrid(r, g, b);
% Now we have created all possible colors.
% Select a number of colors to extract from the total possible colors.
numberOfColors = 10;
randomColors = sort(randperm(numel(rr), numberOfColors))
% These are the indexes of the randomly chosen colors.
fprintf('Just chose %d colors from a possible pallette of %d colors.\n',...
  numberOfColors, numel(rr));

% Make "numberOfColors" plots, with 25 data points in each plot.
x = 1:25;
y = rand(numberOfColors, length(x));
% These y would all be on top of each other.
% Separate the plots vertically.
offsets = repmat((1:numberOfColors)', [1, length(x)]);
y = y + offsets; 
% Extract a subset of "numberOfColors" colors from the total possible 11x11x11 colors.
selectedColors = [rr(randomColors)', gg(randomColors)', bb(randomColors)'];
% Plot "numberOfColors" lines, one in each color.
for p = 1 : numberOfColors
  % Get the index of this random color in the colormap.
  thisIndex = randomColors(p);
  % Get the RGB value from the arrays.
  thisColor = [rr(thisIndex), gg(thisIndex), bb(thisIndex)];
  plot(x, y(p,:), 'Color', thisColor, 'LineWidth', 3);
  hold on;
end
caption = sprintf('%d plots with very different colors', numberOfColors);
title(caption, 'FontSize', fontSize);
xlabel('X', 'FontSize', fontSize);
ylabel('Y', 'FontSize', fontSize);
grid on;