plotting a set of irregular data points

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Yair 2019-1-17

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https://ww2.mathworks.cn/matlabcentral/answers/440167-plotting-a-set-of-irregular-data-points

评论： Luna 2021-1-11

Hello,

I have a set of data points with columns as follows:

cart = cartesian coordinates; sph=spherical coordinates

I want to plot these data points on a 3D plot where x-axis is theta, y-axis is phi, and color is the intensity.

If for example theta has values 0:5:180 degrees and for every theta value there are these phi values 0:10:360 degrees then I can arrange a matrix and use imagesc.

The problem with my set of data points is that the theta and phi values are irregular meaning they are scattered on a sphere. Some data points can have the same theta but different phi, some have same phi but different theta and other points may have unique theta and phi. Like I said, these are points are scattered on a sphere.

Is there any way I can plot these data points so that intensity will be represented by color?

Thank you.

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Answer 1

Luna 2019-1-17

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https://ww2.mathworks.cn/matlabcentral/answers/440167-plotting-a-set-of-irregular-data-points#answer_356767

编辑：Luna 2019-1-17

在 MATLAB Online 中打开

Hi,

You can use scatter3 function to create a 3D scatter plot.

Check the link: scatter3

For coloring the intensity search for colormap and colorbar.

You can use predefined (Matlab's built-in) colormaps' each row according to your intensity data while looping in scatter. Something like this:

% data
[x, y] = meshgrid(1:100);
z = cos(x).^2 + sin(y).^2;
intensityVector = randi(20,numel(x),1);
c = jet(numel(x)); % create your own colormap here with Mx3 matrix
%xdata,ydata,zdata scatter plot, marker size 10, color is c Matrix
scatter3(x(:),y(:),z(:),10,c);
% define colomap and colorbar according the your colormap
colormap(c);
colorbar;