irfft: Warn about asymmetric apodization and don't change default behaviour.

Author: stuart-cls

orangecontrib/spectroscopy/irfft.py

@@ -1,4 +1,5 @@
 from enum import IntEnum
+import warnings
 
 import numpy as np
 
@@ -220,11 +221,19 @@ class IRFFT():
     def __init__(self, dx,
                  apod_func=ApodFunc.BLACKMAN_HARRIS_3, zff=2,
                  phase_res=None, phase_corr=PhaseCorrection.MERTZ,
-                 peak_search=PeakSearch.MAXIMUM, apod_asym=False,
+                 peak_search=PeakSearch.MAXIMUM, apod_asym=None,
                 ):
         self.dx = dx
         self.apod_func = apod_func
-        self.apod_asym = apod_asym
+        if apod_asym is None:
+            warnings.warn(
+                "Apodization symmetry must now be specified.\n"
+                "Defaulting to previous asymmetric behaviour, which is not appropriate for symmetric interferometers (FT-IR).\n"
+                "See Quasars/orange-spectroscopy#641 for details.",
+                category=FutureWarning)
+            self.apod_asym = True
+        else:
+            self.apod_asym = apod_asym
         self.zff = zff
         self.phase_res = phase_res
         self.phase_corr = phase_corr
@@ -247,7 +256,7 @@ def __call__(self, ifg, zpd=None, phase=None):
         # Calculate phase on interferogram of specified size 2*L
         L = self.phase_ifg_size(ifg.shape[0])
         if L == 0: # Use full ifg for phase
-            ifg = apodize(ifg, self.zpd, self.apod_func)
+            ifg = apodize(ifg, self.zpd, self.apod_func, self.apod_asym)
             ifg = zero_fill(ifg, self.zff)
             # Rotate the Complete IFG so that the centerburst is at edges.
             ifg = np.hstack((ifg[self.zpd:], ifg[0:self.zpd]))

orangecontrib/spectroscopy/tests/test_irfft.py

@@ -5,7 +5,7 @@
 
 from orangecontrib.spectroscopy.data import getx
 
-from orangecontrib.spectroscopy.irfft import (IRFFT, zero_fill, PhaseCorrection,
+from orangecontrib.spectroscopy.irfft import (IRFFT, ComplexFFT, zero_fill, PhaseCorrection,
                                               find_zpd, PeakSearch, ApodFunc,
                                               MultiIRFFT, apodize,
                                               )
@@ -78,6 +78,7 @@ def test_agilent_fft_sc(self):
         dx_ag = (1 / 1.57980039e+04 / 2) * 4
         fft = IRFFT(dx=dx_ag,
                     apod_func=ApodFunc.BLACKMAN_HARRIS_4,
+                    apod_asym=False,
                     zff=1,
                     phase_res=None,
                     phase_corr=PhaseCorrection.MERTZ,
@@ -120,6 +121,7 @@ def test_multi(self):
         dx_ag = (1 / 1.57980039e+04 / 2) * 4
         fft = MultiIRFFT(dx=dx_ag,
                          apod_func=ApodFunc.BLACKMAN_HARRIS_4,
+                         apod_asym=False,
                          zff=1,
                          phase_res=None,
                          phase_corr=PhaseCorrection.MERTZ,
@@ -177,3 +179,9 @@ def test_apodization(self):
                     # Apodization should not change value at zpd
                     # Ramp should reduce zpd value by half
                     self.assertAlmostEqual(ifg[zpd] * ramp_value, out[zpd])
+
+    def test_apod_asym_warning(self):
+        for FFT in IRFFT, MultiIRFFT, ComplexFFT:
+            with self.assertWarns(FutureWarning):
+                fft = FFT(dx=dx)
+            self.assertTrue(fft.apod_asym)