imagesc color map for gridded value

Hi all,

I have a set of three variables of a big data set in a given grid (see below) and I would like to plot Z variables as color scale using imagesc. Could you help me how I can plot?

X = 1:01:5

Y =5:01:8

Z = 1,5,0,10,......

length(X)=length(Y)=length(Z).

Answer 1

[Ayush]

Hi,

To plot the Z variable as a colour scale using "imagesc" in MATLAB, you need to ensure that Z is in a matrix form that corresponds to the grid defined by X and Y. If Z is a vector, you need to reshape it into a matrix that matches the dimensions of the grid defined by X and Y. Refer to an example code below for better understanding:

% Define the variables
X = 1:1:5;
Y = 5:1:8;
Z = [1, 5, 0, 10, 2, 3, 4, 7, 6, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19];

% Ensure Z is reshaped into a matrix form
% Here, assuming Z corresponds to a 5x4 grid
Z_matrix = reshape(Z, [length(Y), length(X)]);

% Plot using imagesc
imagesc(X, Y, Z_matrix);

% Set axis properties
set(gca, 'YDir', 'normal'); % To have Y-axis in the correct direction
colorbar; % Display color scale
xlabel('X-axis');
ylabel('Y-axis');
title('Z variable color scale plot');

For more information on the "imagesc" function, refer to the below documentation:

https://www.mathworks.com/help/matlab/ref/imagesc.html

[DGM]

This isn't what the question was asking -- at least not directly. Preparing the data is the core of the problem.

As per the question,

length(X) = length(Y) = length(Z)

So all inputs are equal-length vectors specifying scattered data. Simply reshaping Z doesn't work. The data needs to be interpolated onto a grid using griddata() or scatteredInterpolant().