Convert complex entries in a matrix to their magnitude

Question

I have matrix say a in matlab. I wish to some feature selection using relieff function.

The problem I have is that some values in the matrix are complex numbers. How can I convert the complex numbers to represent their magnitude in the matrix?

Answer 1

You can find the complex valued entries in your matrix A using

cmplx = imag(A) ~= 0; 

Once you found them, you can replace them

A(cmplx) = abs( A(cmplx) );

Note that requiring floating-point numbers to be exactly zero might be too restrictive and a threshold might be needed instead, eg,

cmplx = abs( imag(A) ) > 1e-8;