how do i plot 3 sets of data using different colors based on one data set

hi,

i read a csv file into matlab using csvread and i assign each column (vector) of data with a specific name like time, data1, data2 (data1 and data2 are integers, time data is not). i know how to do a simple plot(time,data1,'.') but what i would like to do is "colorize" data1 according to the values in data2.

thanks for your help!

Todd

Answer 1

[Adam Jurhs]

Image Analyst, i'm confused. in your plot i see 4 unique colors. i don't know how to apply your cmap line of code to my data2. can you please re-write that line using the array

data2=[34,189,34,56,24,42,10087,6,56,34,189,189,10087,24,34,6,189,56,189,189];

so that there are 7 unique colors

[Image Analyst]

Please stop adding Answers. If you want to reply to someone, use the comment box below their answer.

[Adam Jurhs]

hi Image Analyst, thanks for your help! and i'll try to remember to use the comment box

[Image Analyst]

Did you see my answer that had 7 unique colors?

[Adam Jurhs]

yep and that solved the problem, thanks!!!

Answer 2

[Image Analyst]

Try this:

% Assign variables.
t=[0, 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19] ;
data1=[2,3,1,5,8,12,8,5,3,8,8,15,8,5,9,12,3,2,5,5] ;
data2=[34,189,34,56,24,56,189,34,56,34,189,189,189,24,34,189,189,56,189,189];
% Make a colormap
cmap = jet(max(data2));
% Let's say data2 is the row of the colormap which represents the color for
% the marker that we want to draw data 1 in.
for k = 1 : numel(data1)
    % Get a color (1x3 array) from the row corresponding to data2(k).
    % We will plot data1 with that color.
    thisColor = cmap(data2(k), :);
    % Plot a marker for this point of data 1 in this color.
    plot(t(k), data1(k), '.', 'Color', thisColor, 'MarkerSize', 50); % Adjust marker size as needed.
    hold on;
end
grid on;
xlabel('Time')
ylabel('Signal')

[Image Analyst]

@Adam Jurhs's "Answer" moved here:

hi Image Analyst,

Using your code my "real" data only gives 2 data colors, but there are 7 unique values in data2. notice that your plot only gives 3 unique colors but there are 4 unique values in data2. can you please try using the following data2 which has 7 unique values like my "real" data does:

data2=[34,189,34,56,24,42,10087,6,56,34,189,189,10087,24,34,6,189,56,189,189];

Thanks!

[Image Analyst]

Sorry, but with the data2 you gave, there are only 4 unique colors, not 7. And my code makes 4 colors, not 3. Here is proof:

data2=[34,189,34,56,24,56,189,34,56,34,189,189,189,24,34,189,189,56,189,189];
fprintf('The number of unique colors in data2 is %d.\n', length(unique(data2)))

The number of unique colors in data2 is 4.

However two of the dark blues are close in color. Let's try it with random colors.

% Assign variables.
t=[0, 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19] ;
data1=[2,3,1,5,8,12,8,5,3,8,8,15,8,5,9,12,3,2,5,5] ;
data2=[34,189,34,56,24,56,189,34,56,34,189,189,189,24,34,189,189,56,189,189];
% Make a colormap
cmap = rand(max(data2), 3);
% Let's say data2 is the row of the colormap which represents the color for
% the marker that we want to draw data 1 in.
for k = 1 : numel(data1)
    % Get a color (1x3 array) from the row corresponding to data2(k).
    % We will plot data1 with that color.
    thisColor = cmap(data2(k), :);
    % Plot a marker for this point of data 1 in this color.
    plot(t(k), data1(k), '.', 'Color', thisColor, 'MarkerSize', 50); % Adjust marker size as needed.
    hold on;
end
grid on;
xlabel('Time')
ylabel('Signal')

[Image Analyst]

@Adam Jurhs's "Answer" moved here:

Image Analyst, i'm confused. in your plot i see 4 unique colors. i don't know how to apply your cmap line of code to my data2. can you please re-write that line using the array

data2=[34,189,34,56,24,42,10087,6,56,34,189,189,10087,24,34,6,189,56,189,189];

so that there are 7 unique colors

[Image Analyst]

Try this to get 7 unique colors:

% Demo by Image Analyst
% Initialization Steps.
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;
% Assign variables.
t=[0, 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19] ;
data1=[2,3,1,5,8,12,8,5,3,8,8,15,8,5,9,12,3,2,5,5] ;
data2=[34,189,34,56,24,42,10087,6,56,34,189,189,10087,24,34,6,189,56,189,189];
fprintf('The number of unique colors in data2 is %d.\n', length(unique(data2)))

The number of unique colors in data2 is 7.

numUniqueColors = length(unique(data2));
% Assign an index, or group number to each integer so we know which color number it is.
colorIndex = findgroups(data2)

colorIndex = 1×20

3 6 3 5 2 4 7 1 5 3 6 6 7 2 3 1 6 5 6 6

% Make a colormap
cmap = turbo(numUniqueColors);
% Let's say data2 is the row of the colormap which represents the color for
% the marker that we want to draw data 1 in.
for k = 1 : numel(data1)
    % Get a color (1x3 array) from the row corresponding to data2(k).
    % We will plot data1 with that color.
    thisColorIndex = colorIndex(k);
    thisColor = cmap(thisColorIndex, :);
    % Plot a marker for this point of data 1 in this color.
    plot(t(k), data1(k), '.', 'Color', thisColor, 'MarkerSize', 50); % Adjust marker size as needed.
    hold on;
end
grid on;
xlabel('Time')
ylabel('Signal')

[Adam Jurhs]

this solution does answer the question, what i don't know is how to mark it as so

[Image Analyst]

There is a link beside each answer. You saw it and clicked the one next to your answer instead of the one next to mine. You can still click the "Vote" icon to award any answerers "Reputation points". You can accept only one answer (and you can unaccept them and accept different ones if you want) though you can "Vote" for as many as you want. So that's how it works. Anyway, glad my solution works, and note it works for however many unique values you have in data2 -- it doesn't have to be 4 or 7, it can be anything so it's really general.

Answer 3

[Image Analyst]

Don't call a variable time since I think that is a built in function.

So, try this:

% Read in data
data = readmatrix(fileName);
% Get variables from columns.
t = data(:, 1); % Time is column 1
data1 = data(:, 2); % data1 is in column 2.
data2 = data(:, 3); % data1 is in column 3.
% Make a colormap
cmap = jet(length(data1));
% Let's say data2 is the row of the colormap which represents the color for
% the marker that we want to draw data 1 in.
for k = 1 : numel(data1)
    % Get a color (1x3 array) from the row corresponding to data2(k).
    % We will plot data1 with that color.
    thisColor = cmap(data2(k), :);
    % Plot a marker for this point of data 1 in this color.
    plot(t(k), data1(k), '.', 'Color', thisColor, 'MarkerSize', 20); % Adjust marker size as needed.
    hold on;
end
grid on;
xlabel('Time')
ylabel('Signal')

If you have any more questions, then attach your data and code to read it in with the paperclip icon after you read this:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

Answer 4

[Abderrahim. B]

Hi!

Since you did not share your data to test .. I am creating some dummy !

clear
close all
% Create some sample data:
time = 0:99;  % X data
data1 = 2*time  + 0.1;  % Y data
data2 = 1:100;                % "Color" data


% Plot data:
figure
surf([time(:) time(:)], [data1(:) data1(:)], [data2(:) data2(:)], ...    
     'EdgeColor', 'interp', ... 
     'LineWidth', 2);            
view(2); 

% Annotate the plot
xlabel("Time")
ylabel("Data1")

 % Add a colorbar
c = colorbar; 
c.Label.String = "Data2" ;

Hope this helps

Answer 5

[Adam Jurhs]

hi Abderrahim,

your 1st code runs, and i think it is on the right track, but it only plots out the first set of data assigning only one color to that first set. the actual data exist on a different system and i'm not able to transfer that data from one system to another, so here's some "dummy" data

t=[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]

data1=[2,3,1,5,8,12,8,5,3,8,8,15,8,5,9,12,3,2,5,5]

data2=[34,189,34,56,24,56,189,34,56,34,189,189,189,24,34,189,189,56,189,189]

i want to plot t vs. data1 and "colorize" data1 according to the data in data 2. so the first data point in data1 (the number 2) would get a color assigned to it because it is associated with the number 34 in data2. then the number 3 in data1 would get a different color because it is associated with the number 189 in data2, then the number 1 in data1 would get the same color associated with the number 34 from data2, then the number 5 in data1 would get a different color because it is associated with the number 56 in data2, and the pattern repeats. so although the values in the data1 vector differ at each position in the vector, they get "colorized" according to the value of the data point in data2

thank you so much for your help!

Todd

[Image Analyst]

Explain what t to use, since t is longer than either data1 or data2. So you want the first 20 elements, last 20 elements, or do you want to lengthen data1 or data2 to be the same length as t? Explain why they're different lengths.

[Abderrahim. B]

@Adam Jurhs

Maybe scatter will work for you

clear
time =[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]  ;
data1=[2,3,1,5,8,12,8,5,3,8,8,15,8,5,9,12,3,2,5,5]  ;
data2=[34,189,34,56,24,56,189,34,56,34,189,189,189,24,34,189,189,56,189,189] ;

% Plot data:
figure
sc = scatter(time, data1, [], data2, 'filled') ;
sc.SizeData = 100;
% Annotate the plot
xlabel("Time")
ylabel("Data1")
 % Add a colorbar
c = colorbar; 
c.Label.String = "Data2" ;

Answer 6

[Adam Jurhs]

I only get 2 colors on my plot? in my "real" data I have 7 distinct colors

Notice on your plot you only get 3 colors but there are four distinct color assignments the numbers 34, 189, 56, and 24.

Let's change data 2 to have 7 color assignments so that now equals

data2=[34,189,34,56,24,42,10087,6,56,34,189,189,10087,24,34,6,189,56,189,189];
fprintf('The number of unique colors in data2 is %d.\n', length(unique(data2)))

The number of unique colors in data2 is 7.

[Image Analyst]

Who was this "Answer" supposed to actually be a "Comment" to?

[Adam Jurhs]

you gave the solution, i'm just confused by how this forum works dfor marking a thread answered

[Image Analyst]

Here is how it works according to my understanding:

Next to each answer there should be a link that says "Accept this answer" and some icons like a thumbs up that says "Vote". If you Accept an answer, it will move to the top and on the main screen it will put a green box around the number of answers meaning that one of the answers has been accepted. You can only accept one answer. Only the original poster can accept an answer. The original poster can also unaccept an answer. Moderators/editors above some level can also unaccept an answer but only after a week.

You can "Vote" for any number of answers. Anybody, not only the original poster, can Vote for an answer.

You can both Accept and Vote for a single answer if you want.

Accepting and Voting for an answer both give the answere 2 reputation points.

[Adam Jurhs]

sounds mighty complicated for to me.

i don't see the "Accept this answer" next to your answer or i would have checked it, but i can "Vote" for it so i will