add fft frequency transformation for data where the sampling rate must be at least twice the signal bandwidth

Author: SaraPido

sigpro/basic_primitives.py

@@ -34,6 +34,13 @@ class FFTFreq(primitive.FrequencyTransformation):
 
     def __init__(self):
         super().__init__("sigpro.transformations.frequency.fftfreq.fft_freq")
+        
+
+class FFTFreqAllBand(primitive.FrequencyTransformation):
+    """FFT Freq primitive class."""
+
+    def __init__(self):
+        super().__init__("sigpro.transformations.frequency.fftfreq.fft_freq_allband")
 
 
 class FFTReal(primitive.FrequencyTransformation):

sigpro/primitives/sigpro/transformations/frequency/fftfreq/fft_freq_allband.json

@@ -0,0 +1,30 @@
+{
+    "name": "sigpro.transformations.frequency.fftfreq.fft_freq_allband",
+    "primitive": "sigpro.transformations.frequency.fftfreq.fft_freq_allband",
+    "classifiers": {
+        "type": "transformation",
+        "subtype": "frequency"
+    },
+    "produce": {
+        "args": [
+            {
+                "name": "amplitude_values",
+                "type": "numpy.ndarray"
+            },
+            {
+                "name": "sampling_frequency",
+                "type": "float"
+            }
+        ],
+        "output": [
+            {
+                "name": "amplitude_values",
+                "type": "numpy.ndarray"
+            },
+            {
+                "name": "frequency_values",
+                "type": "numpy.ndarray"
+            }
+        ]
+    }
+}

sigpro/transformations/frequency/fftfreq.py

@@ -19,3 +19,21 @@ def fft_freq(amplitude_values, sampling_frequency):
     frequency_values = np.fft.fftfreq(len(amplitude_values), 1 / sampling_frequency)
 
     return np.array(amplitude_values), np.array(frequency_values)
+
+def fft_freq_allband(amplitude_values, sampling_frequency):
+    """Compute the Frequency having FFT values.
+
+    Args:
+        amplitude_values (np.ndarray):
+            A numpy array with the fft values.
+        sampling_frequency (int or float):
+            Sampling frequency value passed in Hz.
+    Returns:
+        tuple:
+            * `amplitude_values (numpy.ndarray)`
+            * `frequency_values (numpy.ndarray)`
+    """
+    
+    frequency_values = np.arange(0, len(amplitude_values)) * sampling_frequency
+
+    return np.array(amplitude_values), np.array(frequency_values)

tests/unit/transformations/frequency/test_fftfreq.py

@@ -0,0 +1,19 @@
+"""Tests for sigpro.transformations.frequency module."""
+import numpy as np
+from sigpro.transformations.frequency import fft_freq_allband
+
+
+
+def test_fft_freq_allband():
+    # setup
+    amplitude_values = [1.5, -0.5, 2.0, 0.5, -1.0]
+    sampling_frequency = 2  # in Hz
+
+    # run
+    amplitude_result, frequency_result = fft_freq_allband(amplitude_values, sampling_frequency)
+
+    # assert
+    expected_amplitude_values = np.array([1.5, -0.5, 2.0, 0.5, -1.0])
+    expected_frequency_values = np.array([0., 2., 4., 6., 8.])
+    np.testing.assert_array_almost_equal(amplitude_result, expected_amplitude_values)
+    np.testing.assert_array_almost_equal(frequency_result, expected_frequency_values)