add frequency fft primitive to basic primitive

Author: SaraPido

sigpro/basic_primitives.py

@@ -28,6 +28,11 @@ class FFT(primitive.FrequencyTransformation):
     def __init__(self):
         super().__init__("sigpro.transformations.frequency.fft.fft")
 
+class FFTFreq(primitive.FrequencyTransformation):
+     """FFT Freq primitive class."""
+     def __init__(self):
+         super().__init__("sigpro.transformations.frequency.fftfreq.fft_freq")
+
 
 class FFTReal(primitive.FrequencyTransformation):
     """FFTReal primitive class."""

…pro/transformations/amplitude/fftfreq.py …pro/transformations/frequency/fftfreq.pysigpro/transformations/amplitude/fftfreq.py renamed to sigpro/transformations/frequency/fftfreq.py sigpro/transformations/amplitude/fftfreq.py renamed to sigpro/transformations/frequency/fftfreq.py

@@ -1,6 +1,3 @@
-"""Build power spectrum from amplitude values."""
-
-
 import numpy as np