Add a utility function to return a dct basis

JohnVinyard · Feb 6, 2018 · 6678d0f · 6678d0f
1 parent d7d1c9b
commit 6678d0f
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diff --git a/zounds/spectral/__init__.py b/zounds/spectral/__init__.py
@@ -21,4 +21,5 @@
 from frequencyadaptive import FrequencyAdaptive
 
 from functional import \
-    fft, stft, apply_scale, frequency_decomposition, phase_shift, rainbowgram
+    fft, stft, apply_scale, frequency_decomposition, phase_shift, rainbowgram, \
+    dct_basis
diff --git a/zounds/spectral/functional.py b/zounds/spectral/functional.py
@@ -104,6 +104,13 @@ def rainbowgram(time_frequency_repr, colormap=cm.rainbow):
     return arr
 
 
+def dct_basis(size):
+    r = np.arange(size)
+    basis = np.outer(r, r + 0.5)
+    basis = np.cos((np.pi / size) * basis)
+    return basis
+
+
 def frequency_decomposition(x, sizes):
     sizes = sorted(sizes)