how to set a limit in each color in a color bar?

Hi! So I want a color bar with only three colors (no gradient). I did:

A = [1; 2; 3; 4]; B = [10; 20; 30; 40]; C = [5; 10; 20; 30]; pointsize = 50;

scatter(A,B, pointsize, C);

colormap([0 1 0; 1 1 0; 1 0 0]) % apply colormap - three colors

caxis([0, 50]) %limits of the color bar

colorbar % show color bar

However, I want the colors to have specific intervals. Like: - green between 0 and 9 - yellow between 10 and 40 - red between 41 and 50

Can someone help me? Thank you!!

Answer 1

[alice]

You only use three colors, so you can change caxis value in order to have the values you want at the limit because the colors, knowing that it will create 3 equal length colors. Then change the limits of the axe. So you can add to your code:

limitGreenYellow = 9.5;
limitYellowRed = 40.5;
caxis([2*limitGreenYellow-limitYellowRed, 2*limitYellowRed-limitGreenYellow]) %limits of the color bar
c=colorbar; % show color bar
xlim(c,[min(limitValues),max(limitValues)]);

Another (better?) way to get what you want would be to have a huge colormap, 1 row for every integer, and it would work for more than 3 colors:

limits = [0,9,10,40,41,50];
colormap([repmat([0 1 0],limits(2)-limits(1)+1,1); repmat([1 1 0],limits(4)-limits(3)+1,1); repmat([1 0 0],limits(6)-limits(5)+1,1)]);
caxis([0, 50]) %limits of the color bar

[Melissa Buechlein]

Thank you for posting this code, it is very helpful. I want to do a similar thing, but my break points are:

[0 0.33 1 2.5 5 11 23 50 120];

I tried multiplying everything by 100, but the breaks don't line up with where I want them. Also, I have several break points that appear the same color.

Here is the code I am using:

limits = [0 33 34 100 101 2500 2501 500 501 1100 1101 2300 2301 3500 3501 5000 5001 12000];

colormap([repmat([0.94 0.94 0.94],limits(2)-limits(1),1);...
    repmat([0.9 0.9 0.9],limits(4)-limits(3)+1,1);...
    repmat([0.5 0.5 0.5],limits(6)-limits(5)+1,1);...
    repmat([0.1 0.1 0.1],limits(8)-limits(7)+1,1);...
    repmat([0 1 1],limits(10)-limits(9)+1,1);...
    repmat([0 0 1], limits(12)-limits(11)+1,1);...
    repmat([1 1 0], limits(14)-limits(13)+1,1);...
    repmat([1 0.7 0], limits(16)-limits(15)+1,1);...
    repmat([1 0 0], limits(18)-limits(17)+1,1)]);

Please advise!