Nonlinear colormap for data that diverges

39 次查看（过去 30 天）
Jared Erb
Jared Erb 2024-2-10
评论： Voss 2024-2-11
Ran in:
I have data that goes through divergences where the Z value goes from approximately -4000 to 4000 very rapidly in certain regions, but the vast majority of the data is near zero. In the picture below, to be able to see what is going on I had to scale most of the color values to near zero to properly see what is happening. But in doing so, most of the colors are in the tiny sliver near zero and the red and blue take up the rest. I would like to nonlinearly scale the colorbar to be able to see all of the colors being used and greatly shrink the red and blue color part of the bar, with leaving the raw data as is if possible. It would also be nice if the colorbar ticks would vary nonlinear as well, instead of being forced to have a set number between consecutive ticks.
%Simple Model of divergent data
X = linspace(-2,2,501) + 0.002;
Y = linspace(-2,2,501) + 0.002;
%Function with Positive and Negative Divergence, and most values near 0
Z = zeros(501,501);
for i=1:length(X)
for j=1:length(Y)
Z(i,j) = 1/((X(i) - 1)^2 + (Y(j) - 1)^2) - 1/((X(i) + 1)^2 + (Y(j) + 1)^2) + 5*(cos(X(i))+sin(Y(i)));
end
end
%Setting the colormap
factor = 0.3;
cmap = jet(1000);
map = 999*rescale(1000./(1+exp(-factor*([1:1000]-500))));
cmap2 = cmap(1+fix(map),:);
figure('Position',[200,100,1500,730]);
ax=axes;
[X,Y] = meshgrid(X,Y);
surf(X,Y,Z,'linestyle','none');
a = colorbar;
set(ax,'colormap',cmap2)
view([0,90])

请先登录，再回答此问题。

采纳的回答

Voss
Voss 2024-2-10
编辑：Voss 2024-2-11
Ran in:
How about something like this:
%Simple Model of divergent data
X = linspace(-2,2,801) + 0.002;
Y = linspace(-2,2,501) + 0.002;
%Function with Positive and Negative Divergence, and most values near 0
Z = 1./((X - 1).^2 + (Y.' - 1).^2) - 1./((X + 1).^2 + (Y.' + 1).^2) + 5*(cos(X)+sin(Y.'));
Z_scaled = sign(Z).*log10(1+abs(Z));
figure('Position',[200,100,1500,730]);
surf(X,Y,Z_scaled,'LineStyle','none')
view(2)
colormap(jet(1000))
cb = colorbar();
tl = [-10.^(5:-1:1) 0 10.^(1:5)];
cb.Ticks = sign(tl).*log10(1+abs(tl));
cb.TickLabels = tl;
Edited to use Z_scaled = sign(Z).*log10(1+abs(Z)); instead of Z_scaled = sign(Z).*log10(abs(Z));
  6 个评论
显示 4更早的评论
Jared Erb
Jared Erb 2024-2-11
Yes, this is exactly what I wanted! Thank you so very much for all your help!

请先登录，再进行评论。

更多回答（1 个）

Morgan
Morgan 2024-2-10
Ran in:
Would something like this work for you?
% CALCULATE MESHGRID
xa = linspace(-2,2,501) + 0.002;
ya = linspace(-2,2,501) + 0.002;
[X,Y] = meshgrid(xa,ya);
% CALCULATE Z
Z = 1./((X - 1).^2 + (Y - 1).^2) - 1./((X + 1).^2 + (Y + 1).^2) + 5*(cos(X)+sin(Y));
% SCALE Z
ZS = sign(Z).*abs(log10(Z));
surf(X,Y,ZS)
axis equal tight
shading interp
colorbar;
view([ 0 90 ])
  3 个评论
显示 1更早的评论
Jared Erb
Jared Erb 2024-2-10
Unforunately that doesn't work for negative values, but I would like to have a nonlinearity that isn't log based, as I couldn't get any log scaling to work correctly.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Red 的更多信息

标签

产品


版本

R2022a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by