Properly trim wavelet packet node coefficients during reconstruction #448
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inverse transforms may produce excess coefficients for some sizes and boundary modes. these need to be trimmed at the Node level as implemented here. This commit fixes PyWavelets#447
trimming is now done at the Node level, so this is redundant.
rgommers
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Feb 4, 2019
grlee77
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I made the change We will probably then be ready to do a new maintenance release from that branch. |
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Thanks @grlee77, looks good to me, merged |
grlee77
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Feb 15, 2019
backport of #448 (fix coefficient shape mismatch in WaveletPacket reconstruction)
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For some boundary modes and data sizes, round-trip DWT/IDWT can results in an output that has an additional coefficient. Here is a simple 1D example where roundtrip transform of a length 17 signal gives a length 18 output:
pywt.waverec(pywt.wavedec(np.arange(17), 'db3', level=3), 'db3').shape
There is some existing logic that seems intended to trim the extra coefficients during wavelet packet transforms:
pywt/pywt/_wavelet_packets.py
Lines 570 to 572 in f0f4ee0
However, this really needs to be done at the
Noderather thanWaveletPacketlevel as indicated by the shape problem raised in #447.closes #447