Contourf plot in discrete range

Question

Bijay Guha 2018-8-4

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https://ww2.mathworks.cn/matlabcentral/answers/413528-contourf-plot-in-discrete-range

编辑： Walter Roberson 2019-3-1

Picture1.png

I have a matrix the values of which ranges from ~0.000001 to ~0.004. I want to separate the colors like this.. 1e-6 to 2e-6 (one color), 2e-6 to 5e-6 (next color), then 5e-6 to 1e-5, 1e-5 to 2e-5, 2e-5 to 5e-5, 5e-5 to 1e-4, 1e-4 to 2e-4, 2e-4 to 5e-4, 5e-4 to 1e-3, 1e-3 to 2e-3, 2e-3 to 3e-3, then 3e-3 to higher values. Here, 1e-6 = 0.000001. Somehow I managed to give different range of values to different colors, but the whole discrete set of ranges is not showed up in the caxis. It only showed discrete range in caxis for values higher than 0.0005, values below that, i.e. 0 to 0.0005 shown only by a single color. Similar to the attached picture is what I want..Could anyone please help..?? Thanks in advance

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Answer 1

KSSV 2018-8-7

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https://ww2.mathworks.cn/matlabcentral/answers/413528-contourf-plot-in-discrete-range#answer_331838

编辑：KSSV 2018-8-7

在 MATLAB Online 中打开

[Z,txt,raw] = xlsread('data.xlsx') ;
Z(Z==-9999) = NaN ;
pcolor(Z) ;
shading interp 
colorbar
%%Fix Ranges
R = [5e-6 1e-5 ;1e-5 2e-5; 2e-5 5e-5; 5e-5  1e-4; 1e-4 2e-4;2e-4 5e-4; 5e-4 1e-3; 1e-3 2e-3; 2e-3 3e-3 ;3e-3 inf] ; 
C = rand(size(R,1),3) ;  % fix random colors, you can use your custom RGB colors here
A = Z ;
for i = 1:size(R,1) 
    idx = Z>=R(i,1) & Z< R(i,2) ;
    A(idx) = R(i,2) ;
end
figure
shading interp 
pcolor(A)
shading interp
colorbar
colormap(C)

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KSSV 2018-8-7

YOu try changing the ranges in R

Bijay Guha 2018-8-7

but I need those ranges only

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Answer 2

Marco Sandoval 2019-3-1

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https://ww2.mathworks.cn/matlabcentral/answers/413528-contourf-plot-in-discrete-range#answer_363437

Hi..

I have the same question. Any luck?

The solution given above is not 100% correct, because it is changing the real values to the upper limit of each range, and when you do a pcolor graph, it doesn't looks like the original.. instead it's seems very rude, as low resolution.

Is there a way of manage the range of numbers of each color in a discrete palette? I mean, something like:

between -inf and 20, one color (considering all real numbers in between)

between 20 and 40, other color

... etc.

I have seen solutions but with surf and scatter functions (because they have an option for colors), but I'm asking for pcolor or contourf.

regards!