Frequency primitive

sigpro/basic_primitives.py

@@ -29,6 +29,13 @@ 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."""
 

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

@@ -0,0 +1,30 @@
+{
+    "name": "sigpro.transformations.frequency.fftfreq.fft_freq",
+    "primitive": "sigpro.transformations.frequency.fftfreq.fft_freq",
+    "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

@@ -0,0 +1,21 @@
+"""SigPro Transformations Frequency module."""
+
+import numpy as np
+
+
+def fft_freq(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.fft.fftfreq(len(amplitude_values), 1 / sampling_frequency)
+
+    return np.array(amplitude_values), np.array(frequency_values)

tests/unit/transformations/frequency_time/test_stft.py

@@ -19,7 +19,7 @@ def test_stft():
     expected_time_values_len = 3
     value = amplitude_values[0][0]
 
-    assert type(value) == np.complex128
+    assert isinstance(value, np.complex128)
     assert len(amplitude_values) == expected_amplitude_values_len
     assert len(frequency_values) == expected_frequency_values_len
     assert len(time_values) == expected_time_values_len
@@ -39,7 +39,7 @@ def test_stft_real():
     expected_time_values_len = 3
     value = amplitude_values[0][0]
 
-    assert type(value) == np.float64
+    assert isinstance(value, np.float64)
     assert len(amplitude_values) == expected_amplitude_values_len
     assert len(frequency_values) == expected_frequency_values_len
     assert len(time_values) == expected_time_values_len