fwht | Fast Walsh Hadamard Transform in C | Computer Vision library

This is constructing an FFTW "plan" to perform a multidimensional FFT. The cFFTWPlan type is a wrapper around the C fftw_plan pointer, and is implemented in the FFTW.jl module. The arguments in curly braces are Julia type parameters: in this case, indicating the number type (Tc), the FFTW transform direction FORWARD, whether the transform is in-place (X===Y), and the dimensionality of the transform (N). There are two methods here, one for an FWHT of complex-number data that creates a cFFTWPlan (which calls fftw_plan_guru_dft) and one for real-number data that creates an r2rFFTWPlan (which calls fftw_plan_guru_r2r). (These internal types of FFTW.jl are undocumented. The low-level C calls directly to the FFTW library are documented in the FFTW manual.

It should, in principle, be possible to make similar calls to FFTW for NumPy arrays. However, the existing pyFFTW wrappers don't seem to support FFTW's r2r transforms (needed for FWHTs of real data), so you'd have to add that.

Or you could call the Julia Hadamard.jl module from Python via the pyjulia package. Or you could use some other Python FWHT package, like https://github.com/FALCONN-LIB/FFHT

You are concatenating strings with macros, macros are not functions. You can't invoke macros with variables. For example the following program will print "hello world"