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How to adjust colorbar range in a matlab plot

How to adjust colorbar range in a matlab plot

(OP)
Hi everyone,

new to Matlab here. I have a n x m matrix with values in the range 0.0-3.0 aprox. I want to make a plot using only 2 colors: red if value < 1 and green otherwise. I used imagesc with colormap ([1 0 0; 0 1 0]). The problem is that the colorbar divides the range from 0 to 1.5 (red) and 1.5 to 3.0 (green). I suppose it's easy, but I can't found how to change the colorbar limits, in order to get 0.0 to 1.0 = red, and 1.0 to 3.0 = green. Any help?

FGS

RE: How to adjust colorbar range in a matlab plot

Mr Ugly says why not transpose your results matrix to match the colorbar? newX=(X>1)+.5; or something like that. I'm sure you can define a custom colorbar, but I am o a non matlab computer.

Cheers

Greg Locock

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RE: How to adjust colorbar range in a matlab plot

(OP)
Thanks, Greg. I haven't solved my problem yet, just trying alternative solutions like your suggestion. Seems a good idea, i'll try it.

(BTW, sorry for my delay in the response)

FGS

RE: How to adjust colorbar range in a matlab plot

Try this: If the N x M is huge, you save a lot of overhead by just altering the structure contents.

x = [0 1 2 3;1 2 3 0;2 3 0 1;3 0 1 2] % example user array
map = [1 0 0; 0 1 0]; % The red & green primaries wanted

S= imagesc(x) % nice pretty colors, regardless...

CD = get(S,'CData') % Don't wipe the original matrix. Extract the plot data.

CD(find(CD <= 1)) = 0 % user paint scheme. 0 is 1st color
CD(find(CD > 1)) = 1 % 2nd color

set(S,'CData',CD) % 2 Pac Secure, but wrong colors.

colormap(map) % Merry Christmas !
%when you are happy with the results:

colormap % restore the original colors.

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