# Colormap a plot based on value of (x,y)

3 views (last 30 days)
Matthew on 16 Jun 2024
Hello,
I have a table T of dimensions x,y where each point has a value between -100 and 100.
I want to graph this data such that T(1,1) is point 1,1 on the graph and the color of that point is determined by the value of T(1,1)
I included a picture of something similar to what I want my plot to look like, along with some code that generates an example table for graphing
clear
clc
close all
%This will generate a table with example data.
x=100
y=50
data=zeros(y,x);
data(1,1)=50;
dchartdx=25/x;
dchartdy=25/y;
for ii=1:x
data(1,ii+1)=data(1,ii)+dchartdx;
end
for ii=1:x+1
for ij=1:y
data(ij+1,ii)=data(ij,ii)+dchartdy;
end
end
DGM on 16 Jun 2024
Try imagesc(). If you want explicit control over the colormap limits, use clim().
imagesc(data) % display the data with the colormap ends corresponding to the data extrema
colormap(jet(256)) % specify a colormap

Manikanta Aditya on 3 Jul 2024
Hi,
The image you've provided shows a depth vs range plot, likely representing some kind of acoustic or seismic data.
To create a similar plot using MATLAB with your data, you can use the 'imagesc' function as mentioned by @DGM.
Here's the script with the changes:
clear
clc
close all
% Generate example data
x = 100;
y = 50;
data = zeros(y, x);
% Fill the data array (your existing code)
data(1,1) = 50;
dchartdx = 25/x;
dchartdy = 25/y;
for ii = 1:x
data(1,ii+1) = data(1,ii) + dchartdx;
end
for ii = 1:x+1
for ij = 1:y
data(ij+1,ii) = data(ij,ii) + dchartdy;
end
end
% Create the plot
figure;
imagesc(1:x, 1:y, data); % display the data with the colormap ends corresponding to the data extrema
colormap(flipud(hot)); % specify a colormap
% Set axis labels and title
xlabel('Range (km)');
ylabel('Depth (m)');
title('Data Visualization');
% Invert the y-axis to have (1,1) at the top-left corner
set(gca, 'YDir', 'reverse');
% Adjust aspect ratio if needed
axis equal tight
I hope this helps!

### Categories

Find more on Colormaps in Help Center and File Exchange

R2023b

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!