How to sum of the values of z corresponding to the ranges of x and y?

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SOM 2023-3-20

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评论： Rik 2023-3-22

Hello,

I have a 3D matrix (x, y ,z) such as:

[1 -5 -2; 0 2 3; 2 -5 -2; -0.5 2 5; -0.8 3 3.5]

Can we find the sum of the values of z corresponding to the ranges of x and y in x, y and z?

For simple example, the sum of z values corresponding to -1<x<1 and 1<y<5.

Any suggestions?

Thank you!

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Answer 1

Rik 2023-3-20

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If your ranges grow more complex, you should try to define groups so you can use splitapply. But for this simple example you can simple use logical indexing on your 2D (not 3D) data.

data = [1 -5 -2; 0 2 3; 2 -5 -2; -0.5 2 5; -0.8 3 3.5];
x = data(:,1);
y = data(:,2);
z = data(:,3);
value = sum(z( x>=-1 & x<1 & y>=1 & y<5 ));
disp(value)
   11.5000