How to set specific values in an array to a certain color when using imagesc?

I have an array that is 100x100 filled with zeros. I want to set some cells to other values and have the cell change colour depending on the value.

i want cells that have a value of 1 to be green, a value 2 to be white, 3 to be brown and 0 to be blue.

how would i do this?

Answer 1

[Miriam]

You can define your own colormap as follows:

x = randi([0 3],10,10);
colors = [0 0 1;... % blue for 0
          0 1 0;... % green for 1
          1 1 1;... % white for 2
          0.65 0.16 0.16]; % brown for 3, etc.
      
figure;
imagesc(x);
colormap(colors);

[Selva Kumar]

When there is no '1' or '2' in the matrix 'x', then this colormap doesnot work as intended.

Any solution for this issue ?

[Stephen23]

"Any solution for this issue ?"

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