[Python-modules-team] Bug#510922: python-pywt: wp.reconstruct() might fail with '...must satisfy (0 <= len(cA) - len(cD) <= 1).'

[Yaroslav Halchenko]

Package: python-pywt
Version: 0.1.7~svn97-1
Severity: normal


Yet another obstacle I found while analysing some of my data.
If pruning has occured, wp.reconstruct() might fail when I guess it should have not.

,---
| /usr/lib/python2.4/site-packages/pywt/wavelet_packets.pyc in reconstruct(self, update)
|      85                 raise ValueError, "Can not reconstruct. Tree is missing data"
|      86             else:
| ---> 87                 rec = idwt(data_a, data_d, self.wavelet, self.mode, correct_size=True)
|      88                 if update:
|      89                     self.data = rec
|
| /usr/lib/python2.4/site-packages/pywt/_pywt.so in pywt._pywt.idwt()
|
| ValueError: Coefficients arrays must satisfy (0 <= len(cA) - len(cD) <= 1).
`---

Length at the place of failure are

ipdb> len(data_a)
260
ipdb> len(data_d)
252

behavior stays the same when I change padding mode to 'sym'.
Also problem doesn't occur if none of the nodes got pruned

I am attaching again that example file with embedded data snippet and adjusted
threshold to reproduce the problem.

-- System Information:
Debian Release: lenny/sid
  APT prefers testing
  APT policy: (991, 'testing'), (990, 'unstable'), (300, 'experimental')
Architecture: i386 (i686)

Kernel: Linux 2.6.26-1-686 (SMP w/2 CPU cores)
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/bash

Versions of packages python-pywt depends on:
ii  libc6                         2.7-15     GNU C Library: Shared libraries
ii  python                        2.5.2-2    An interactive high-level object-o
ii  python-central                0.6.8      register and build utility for Pyt
ii  python-numpy                  1:1.1.0-3  Numerical Python adds a fast array

python-pywt recommends no packages.

python-pywt suggests no packages.

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