Can we use more than one colormap in one plot ?

In my data, I have 6 types of roads and then for each road, I have 24 hours of data. In the function below, I am getting 24 plots as output which represent 1-24 hours respectively.

What I need to achieve is I need to show different roads (1-6) in different colorscale so that they can be differentiated. I have tried as under but it does not work. And also, how can print different colorbars associated with different ColorMap ?

PLease help.

function testplotLine
clear all; clc; close all; format short g;
% read data

InFilename = sprintf('Idontknow.csv');
LinkMat = csvread(InFilename);

UniqueHours = sortrows(unique(LinkMat(:,5)));

LinkMat(:,6) = log(LinkMat(:,6)+1);
fprintf('max of Uniquehours %u ', max(UniqueHours));

for j = 1:size(UniqueHours, 1)

      fprintf('Processing hour:%u....',UniqueHours(j));

      RowIndex = find(LinkMat(:,5) == UniqueHours(j));

      fprintf('size of rowindex %u ', size(RowIndex));

      % extract those record and store them into TempMat

      TempMat = LinkMat(RowIndex,:);

      hold on;

   for i = 1:size(TempMat,1)

          z = TempMat(i,6);

          if(TempMat(i,7) == 1)   % this is road type 1
          patch('Vertices', [TempMat(i,1) TempMat(i,2); TempMat(i,3) TempMat(i,4)], 'Faces', [1 2], 'FaceVertexCData', [z; z], 'EdgeColor', 'interp', 'LineWidth', 1.5);

              colormap bone;
          end

          if (TempMat(i,7) == 2) % this is road type 2

              patch('Vertices', [TempMat(i,1) TempMat(i,2); TempMat(i,3) TempMat(i,4)], 'Faces', [1 2], 'FaceVertexCData', [z; z], 'EdgeColor', 'interp', 'LineWidth', 1.5, 'LineStyle', ' - ');

              colormap copper;

          end

          if (TempMat(i,7) == 3)

              patch('Vertices', [TempMat(i,1) TempMat(i,2); TempMat(i,3) TempMat(i,4)], 'Faces', [1 2], 'FaceVertexCData', [z; z],  'EdgeColor', 'interp','LineWidth', 1.5);

              colormap autumn;
          end

          if (TempMat(i,7) == 4)

              patch('Vertices', [TempMat(i,1) TempMat(i,2); TempMat(i,3) TempMat(i,4)], 'Faces', [1 2], 'FaceVertexCData', [z; z], 'EdgeColor', 'interp', 'LineWidth', 1.5);

              colormap summer;
           end

          if (TempMat(i,7) == 5)

              patch('Vertices', [TempMat(i,1) TempMat(i,2); TempMat(i,3) TempMat(i,4)], 'Faces', [1 2], 'FaceVertexCData', [z; z],  'EdgeColor', 'interp','LineWidth', 1.5);
              colormap pink;
          end

          if (TempMat(i,7) == 6)

              patch('Vertices', [TempMat(i,1) TempMat(i,2); TempMat(i,3) TempMat(i,4)], 'Faces', [1 2], 'FaceVertexCData', [z; z], 'EdgeColor', 'interp', 'LineWidth', 1.5);
           colormap jet;
              end 

      end

axis off;
set(gca,'position',[0,0, .9, .9]);

colorbar; % I need to print colorbars also....*
hold off;

RootDirectory = 'C:\Users\JSK\Desktop\25March\chutiyapa\more chutiyapa';
OutFileName = sprintf('ORTotHoursCO_Hour_%u.jpg',UniqueHours(j));

TotalFileName = [RootDirectory,'\',OutFileName];
print(TotalFileName)
print('-djpeg','-r300',TotalFileName);
close all;

end
end

Answer 1

[per isakson]

Yes, but it is not simple. See the links in my answer http://www.mathworks.se/matlabcentral/answers/68939#answer_80274

[Walter Roberson]

Or, more properly, "Not really, but you can fake it by following the links that Per gives."

[Jujhar Khurana]

I tried to freeze the colors, it is not giving any error but taking forever to run. And finally I have to stop the process.

[per isakson]

Questions on multiple colormaps appears on a regular basis here and in the Newsgroup.

The tech-note, How do use multiple colormaps in a single figure?, is a solution proposed by The MathWorks. The FAQ refers to this tech-note. I rely on this approach.

There is a blog post, Using multiple colormaps in a single figure, which describes the use of freezeColors.

I cannot guess why you have problems with freezeColors. It is a highly rated FEX contribution.

And one more link: multiple colormaps in matlab

[Jujhar Khurana]

Might be possible that I am doing something wrong, I will check it again. Thanks per isakson and Walter

Answer 2

[Image Analyst]

Jujhar, run my demo and I think you'll be able to see how you can do it for your image by making sure each range of your data occupies a different range of the 256 colors available for the pseudocolor lookup table (colormap).

clc;
clearvars;
close all;
imtool close all;  % Close all imtool figures.
workspace;
format longg;
format compact;
fontSize = 20;

% Read in a standard MATLAB gray scale demo image.
folder = fullfile(matlabroot, '\toolbox\images\imdemos');
baseFileName = 'cameraman.tif';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
  % File doesn't exist -- didn't find it there.  Check the search path for it.
  fullFileName = baseFileName; % No path this time.
  if ~exist(fullFileName, 'file')
    % Still didn't find it.  Alert user.
    errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
grayImage = imread(fullFileName);
% Get the dimensions of the image.  
% numberOfColorBands should be = 1.
[rows columns numberOfColorBands] = size(grayImage);

% The colormap can only be 256 rows long (otherwise it repeats - you can't assign them).
% So make each image only a portion of the 256 gray levels.
% Define a colormap that consists of 4 separate colormaps.
% So make each colormap section 256/4 = 64 rows long.
numberOfImages = 4;
cmap = [gray(256/numberOfImages);...
  jet(256/numberOfImages);...
  copper(256/numberOfImages);...
  winter(256/numberOfImages)];
% Apply the colormap to the figure.
colormap(cmap);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Give a name to the title bar.
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') 

% if there are 4 images, each needs to be displayed in 256/4 or 64 gray levels.
% Use imadjust() to map the original gray image into that range.
% Generate the first image.
subplot(2, 2, 1);
% Map into 0-63.
firstImage = imadjust(grayImage, [], [0 1/numberOfImages]);
% Display image mapped into the new intensity range.
image(firstImage);
caption = sprintf('Gray Level Image mapped into the range 0-63\nso that the Gray colormap will be applied');
title(caption, 'FontSize', fontSize);
colorbar;

% Generate the other images such that
subplot(2, 2, 2);
% Map into 64-127.
secondImage = imadjust(grayImage, [], [1/numberOfImages 2/numberOfImages]);
% Display image mapped into the new intensity range.
image(secondImage);
caption = sprintf('Gray Level Image mapped into the range 64-127\nso that the Jet colormap will be applied');
title(caption, 'FontSize', fontSize);
colorbar;

subplot(2, 2, 3);
% Map into 128-191.
thirdImage = imadjust(grayImage, [], [2/numberOfImages, 3/numberOfImages]);
% Display image mapped into the new intensity range.
image(thirdImage);
caption = sprintf('Gray Level Image mapped into the range 128-191\nso that the Copper colormap will be applied');
title(caption, 'FontSize', fontSize);
colorbar;

subplot(2, 2, 4);
% Map into 192-255.
fourthImage = imadjust(grayImage, [], [3/numberOfImages, 4/numberOfImages]);
% Display image mapped into the new intensity range.
image(fourthImage);
caption = sprintf('Gray Level Image mapped into the range 192-255\nso that the Winter colormap will be applied');
title(caption, 'FontSize', fontSize);
colormap(cmap)
colorbar;

[Image Analyst]

Jujhar - you still there? Did you try any of these answers?

[Jujhar Khurana]

Hello Image Analyst, I am sorry for late reply. I will try and reply to you.

Thank you.

[Jujhar Khurana]

Hi, I run this code. It worked. but my problem is little different. I want to show you a sample picture. Is there a way I can attache here ?

[Image Analyst]

Try posting to snag.gy or tinypic.com

[Jujhar Khurana]

Hello Image Analyst,

Please go this link and find the picture.

http://i45.tinypic.com/2vlvfcn.jpg

This plot has 6 kinds of roads ( which are shown in only a single colormap in this plot ) which have different level of pollutants as you can observe different colors. This plot shows hour 18th of a day. I use a loop to make 24 such plots for 24 hours.

Now, the thing is I need to show each road in different color scale. For example...Raod 1 in Colormap bone....Road 2 in colormap jet etc....

Can you suggest me something ?

Thanks Again.

[Walter Roberson]

Tricky. In order to do that you would have to use transparent figures that overlayed each other, with a different colormap for each road.

It would be much easier if you do not use pseudocolors and instead generated RGB for each item. You can calculate colormap indices for any data point as

min(number_of_colormap_entries, 1 + floor( (datapoint - min_for_this_kind_of_data) ./ (max_for_this_kind_of_data - min_for_this_kind_of_data) * number_of_colormap_entries) )

the min() is to adjust for the fact that values exactly equal to max_for_this_kind_of_data would become 1 exactly after the division, multiply that by the number of entries would give the number of entries exactly, then floor() of that would be the number of entries exactly, add 1 would be 1 more than the number of entries. Any other value than the exact maximum can use the numeric formula. It is possible to tweak the numeric formula instead using eps() appropriately, but it gets harder to understand whether all the boundary cases get done exactly right.

Once you have the indices into the colormap,

rgbimage = reshape( TheColormap(DataIndices(:), :), size(YourData,1), size(YourData,2), 3);

and create an array DataAlpha of the locations where the data is to show up (value 1) or not (value 0). Then,

image(rgbimage, 'AlphaData', DataAlpha)

[Jujhar Khurana]

Hello Walter, Thanks for your input. I will try and will reply back.

Thanks Again.

[Walter Roberson]

Or if your roads are not thick, then use patches to draw them. You can adjust the patch color at each vertex or each edge.

[Jujhar Khurana]

Well, I am using Patches only ( you can in my code above ) and you only suggested me to use it in one of my other questions.

Anyways, please give me one more advice:

What changes do I need to do in my current code(given in the question) ? Becuase the code you suggested above( ofcourse, it will work) but it is completely new for me, so I am not getting how to incorporate it in to my problem....

[Image Analyst]

I'm with Walter - I'd just create a color image - a true color 3D RGB image made up of 3 color planes. You can use imline() to burn a line into each color plane with the appropriate R, G, and B values. I think that's easier than using patch() to create lines.

[Jujhar Khurana]

Thanks All of you.