How to arrange the correct range in colorbar in MATLAB

Question

Torkan 2022-4-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1691115-how-to-arrange-the-correct-range-in-colorbar-in-matlab

评论： Mathieu NOE 2022-4-8

tt.xlsx

Hello,

I have a 3D surface curvefit in matlab. The issue is for Z column the range is outside of the data range. How can I give correct range? This are my data and this is my code and actually it gives me wrong plot maybe. Would you pelase check it? Also, I want to remove the data points from the plot, how to do that?

Or if you have any other way to plot I would ppreciate it

clear all

M=readtable('tt.xlsx');

x1 = M.(1) ;

y1 = M.(2) ;

z1 = M.(3);

s = fit([x1 y1],z1,"poly23");

plot(s,[x1 y1],z1);

c = jet(20);

colormap(c);

shading interp

xlabel('HR')

ylabel('L/D')

zlabel('Fc')

colorbar

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Answer 1

Mathieu NOE 2022-4-7

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1691115-how-to-arrange-the-correct-range-in-colorbar-in-matlab#answer_937320

在 MATLAB Online 中打开

hello

as I don't have the toolbox for fit, I used instead the FEX submission (excellent) from John D'Errico :

polyfitn - File Exchange - MATLAB Central (mathworks.com)

you can simply comment the line with scatter3 plot if you don't want the points on the plot

no issue so far...

code :

clear all
M=readtable('tt.xlsx');
x1 = M.(1) ;
y1 = M.(2) ; 
z1 = M.(3);
s = polyfitn([x1(:) y1(:)], z1(:), 2); % File Exchange by John D'Errico : https://fr.mathworks.com/matlabcentral/fileexchange/34765-polyfitn
[xx,yy] = meshgrid(0:1:10, 0:10:400);
zz = polyvaln(s, [xx(:) yy(:)]);
zz = reshape(zz, size(xx));
% remove data outise range
ind = (zz>=max(z1));
zz(ind) = NaN;
% plot points and surface
figure('Renderer','opengl')
scatter3(x1, y1, z1,'o','filled'); % comment this line if you don't want the points
surface(xx, yy, zz, ...
    'FaceColor','interp', 'EdgeColor','b', 'FaceAlpha',0.4)
AZ = -37.5;
EL = 30;
view(AZ,EL)
grid on; 
colormap(jet);
shading interp 
xlabel('HR')
ylabel('L/D')
zlabel('Fc')
colorbar;

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Mathieu NOE 2022-4-8

在 MATLAB Online 中打开

hello again

first , a small improvement of the code

mesh is shown (can be removed by commenting this line :

mesh(xx, yy, zz, 'FaceAlpha',0.4)

meshgrid limits are computed automatically from min and max values of x1 and y1 (I took 25 steps for both directions, you can of course change that)

[xx,yy] = meshgrid(linspace(min(x1),max(x1),25), linspace(min(y1),max(y1),25));

full code :

clear all
M=readtable('tt.xlsx');
x1 = M.(1) ;
y1 = M.(2) ; 
z1 = M.(3);
s = polyfitn([x1(:) y1(:)], z1(:), 2); % File Exchange by John D'Errico : https://fr.mathworks.com/matlabcentral/fileexchange/34765-polyfitn
[xx,yy] = meshgrid(linspace(min(x1),max(x1),25), linspace(min(y1),max(y1),25));
zz = polyvaln(s, [xx(:) yy(:)]);
zz = reshape(zz, size(xx));
% remove data outside range
ind = (zz>=max(z1));
zz(ind) = NaN;
% plot points and surface
figure('Renderer','opengl')
hold on
scatter3(x1, y1, z1,'o','filled'); % comment this line if you don't want the points
mesh(xx, yy, zz, 'FaceAlpha',0.4)
surface(xx, yy, zz,'FaceColor','interp', 'EdgeColor','b', 'FaceAlpha',0.4)
hold off
AZ = -37.5;
EL = 30;
view(AZ,EL)
grid on; 
colormap(jet);
shading interp 
xlabel('HR')
ylabel('L/D')
zlabel('Fc')
colorbar;
%% NOTA : difference between surf and surface matlab functions 
% The difference is that surf checks first to see if the axes Nextplot property says to replace plot, 
% and if so then it does a cla. Then either way it calls surface()
% In other words if "hold on" is not in effect (or the internal equivalent) 
% then surf will erase the current plot. surface() will not do that.
% The difference is sort of like the difference between line() and plot(). line() never erases the current plot.
% plot() might erase the current plot, and whether it does or not it will call line to do the drawing work.