fftn numpy in c# using pythonnet #2349

m0hssn · 2024-03-24T12:04:47Z

m0hssn
Mar 24, 2024

I am using pythonnet to integrate python code in my c# program. I'm trying to apply a fft on a complex array the code works in python but when i use it in c# it gives strange errors it says the input must be a real number and not complex which is preposterous

this is he code

using System.Globalization;
using System.Net.Mime;
using System.Numerics;
using Python.Runtime;

static void Initialize()
{
    string pythonDll = @"C:\Users\Mohsen\AppData\Local\Programs\Python\Python39\python39.dll";
    Environment.SetEnvironmentVariable("PYTHONNET_PYDLL", pythonDll);
    PythonEngine.Initialize();    
}


Initialize();
Complex[] complexes = [
    new Complex(1.0, 2.0),
    new Complex(3.0, 4.0),
    new Complex(5.0, 6.0),
    new Complex(5.0, 6.0)

];
List<Complex> comlist = new List<Complex>(complexes);


using (Py.GIL())
{
    dynamic lst = new PyList();
    lst.append(2);
    lst.append(2);

    dynamic tuple = PyTuple.AsTuple(lst);
    dynamic np = Py.Import("numpy");
    dynamic rawData = np.array(comlist);
    rawData.reshape(tuple);
    dynamic k = np.reshape(a: rawData.T, newshape:tuple, order:'F');

    k = np.fft.fftshift(k);
    k = np.fft.fftn(k);

    k = np.fft.fftshift(k);
    k = np.rot90(k);
    k = np.flip(k, axis : 0);
    
    
    k = np.flip(np.rot90(np.fft.fftshift(np.fft.fftn(np.fft.fftshift(k)))));
    Console.WriteLine(k.shape);
}

and here is the exception:

"C:\Program Files\JetBrains\JetBrains Rider 2023.3.4\plugins\dpa\DotFiles\JetBrains.DPA.Runner.exe" --handle=7216 --backend-pid=24644 --etw-collect-flags=67108622 --detach-event-name=dpa.detach.7216 C:/Users/Mohsen/RiderProjects/ConsoleApp2/ConsoleApp2/bin/Debug/net8.0/ConsoleApp2.exe
Unhandled exception. Python.Runtime.PythonException: must be real number, not Complex
  File "C:\Users\Mohsen\AppData\Local\Programs\Python\Python39\lib\site-packages\numpy\fft\_pocketfft.py", line 74, in _raw_fft
    r = pfi.execute(a, is_real, is_forward, fct)
  File "C:\Users\Mohsen\AppData\Local\Programs\Python\Python39\lib\site-packages\numpy\fft\_pocketfft.py", line 185, in fft
    output = _raw_fft(a, n, axis, False, True, inv_norm)
  File "<__array_function__ internals>", line 5, in fft
  File "C:\Users\Mohsen\AppData\Local\Programs\Python\Python39\lib\site-packages\numpy\fft\_pocketfft.py", line 652, in _raw_fftnd
    a = function(a, n=s[ii], axis=axes[ii], norm=norm)
  File "C:\Users\Mohsen\AppData\Local\Programs\Python\Python39\lib\site-packages\numpy\fft\_pocketfft.py", line 755, in fftn
    return _raw_fftnd(a, s, axes, fft, norm)
  File "<__array_function__ internals>", line 5, in fftn
   at Python.Runtime.PythonException.ThrowLastAsClrException()
   at Python.Runtime.PyObject.Invoke(PyTuple args, PyDict kw)
   at Python.Runtime.PyObject.InvokeMethod(String name, PyTuple args, PyDict kw)
   at Python.Runtime.PyObject.TryInvokeMember(InvokeMemberBinder binder, Object[] args, Object& result)
   at CallSite.Target(Closure, CallSite, Object, Object)
   at System.Dynamic.UpdateDelegates.UpdateAndExecute2[T0,T1,TRet](CallSite site, T0 arg0, T1 arg1)
   at Program.<Main>$(String[] args) in C:\Users\Mohsen\RiderProjects\ConsoleApp2\ConsoleApp2\Program.cs:line 38

filmor · 2024-03-25T21:16:38Z

filmor
Mar 25, 2024
Maintainer

complex is not converted automatically, so np.array will build an "array" that contains wrapped Complex objects. You could try using floats instead and reinterpreting the array as complex via numpy's methods.

0 replies

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fftn numpy in c# using pythonnet #2349

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filmor Mar 25, 2024 Maintainer

m0hssn
Mar 24, 2024

filmor
Mar 25, 2024
Maintainer