PyWavelets 1.0.0 Release Notes#

We are very pleased to announce the release of PyWavelets 1.0. We view this version number as a milestone in the project’s now more than a decade long history. It reflects that PyWavelets has stabilized over the past few years, and is now a mature package which a lot of other important packages depend on. A listing of those package won’t be complete, but some we are aware of are:

  • scikit-image - image processing in Python

  • imagehash - perceptual image hashing

  • pyradiomics - extraction of Radiomics features from 2D and 3D images and binary masks

  • tomopy - Tomographic Reconstruction in Python

  • SpikeSort - Spike sorting library implemented in Python/NumPy/PyTables

  • ODL - operator discretization library

This release requires Python 2.7 or >=3.5 and NumPy 1.9.1 or greater. The 1.0 release will be the last release supporting Python 2.7. It will be a Long Term Support (LTS) release, meaning that we will backport critical bug fixes to 1.0.x for as long as Python itself does so (i.e. until 1 Jan 2020).

New features#

New 1D test signals#

Many common synthetic 1D test signals have been implemented in the new function to encourage reproducible research. To get a list of the available signals, call'list'). These signals have been validated to match the test signals of the same name from the Wavelab toolbox (with the kind permission of Dr. David Donoho).

C99 complex support#

The Cython modules and underlying C library can now be built with C99 complex support when supported by the compiler. Doing so improves performance when running wavelet transforms on complex-valued data. On POSIX systems (Linux, Mac OS X), C99 complex support is enabled by default at build time. The user can set the environment variable USE_C99_COMPLEX to 0 or 1 to manually disable or enable C99 support at compile time.

complex-valued CWT#

The continuous wavelet transform, cwt, now also accepts complex-valued data.

More flexible specification of some continuous wavelets#

The continuous wavelets "cmor", "shan" and "fbsp" now let the user specify attributes such as their center frequency and bandwidth that were previously fixed. See more on this in the section on deprecated features.

Fully Separable Discrete Wavelet Transform#

A new variant of the multilevel n-dimensional DWT has been implemented. It is known as the fully separable wavelet transform (FSWT). The functions fswavedecn fswaverecn correspond to the forward and inverse transforms, respectively. This differs from the existing wavedecn and waverecn in dimensions >= 2 in that all levels of decomposition are performed along a single axis prior to moving on to the next.

New thresholding methods#

pywt.threshold now supports non-negative Garotte thresholding (mode='garotte'). There is also a new function pywt.threshold_firm that implements firm (semi-soft) thresholding. Both of the these new thresholding methods are intermediate between soft and hard thresholding.

New anti-symmetric boundary modes#

Two new boundary handling modes for the discrete wavelet transforms have been implemented. These correspond to whole-sample and half-sample anti-symmetric boundary conditions (antisymmetric and antireflect).

New functions to ravel and unravel wavedecn coefficients#

The function ravel_coeffs can be used to ravel all coefficients from wavedec, wavedec2 or wavedecn into a single 1D array. Unraveling back into a list of individual n-dimensional coefficients can be performed by unravel_coeffs.

New functions to determine multilevel DWT coefficient shapes and sizes#

The new function wavedecn_size outputs the total number of coefficients that will be produced by a wavedecn decomposition. The function wavedecn_shapes returns full shape information for all coefficient arrays produced by wavedecn. These functions provide the size/shape information without having to explicitly compute a transform.

Deprecated features#

The continuous wavelets with names "cmor", "shan" and "fbsp" should now be modified to include formerly hard-coded attributes such as their center frequency and bandwidth. Use of the bare names “cmor”. “shan” and “fbsp” is now deprecated. For “cmor” (and “shan”), the form of the wavelet name is now “cmorB-C” (“shanB-C”) where B and C are floats representing the bandwidth frequency and center frequency. For “fbsp” the form should now incorporate three floats as in “fbspM-B-C” where M is the spline order and B and C are the bandwidth and center frequencies.

Backwards incompatible changes#

Python 2.6, 3.3 and 3.4 are no longer supported.

The order of coefficients returned by swt2 and input to iswt2 have been reversed so that the decomposition levels are now returned in descending rather than ascending order. This makes these 2D stationary wavelet functions consistent with all of the other multilevel discrete transforms in PyWavelets.

For wavedec, wavedec2 and wavedecn, the ability for the user to specify a level that is greater than the value returned by dwt_max_level has been restored. A UserWarning is raised instead of a ValueError in this case.

Bugs Fixed#

Assigning new data to the Node or Node2D no longer forces a cast to float64 when the data is one of the other dtypes supported by the dwt (float32, complex64, complex128).

Calling pywt.threshold with mode='soft' now works properly for complex-valued inputs.

A segfault when running multiple swt2 or swtn transforms concurrently has been fixed.

Several instances of deprecated numpy multi-indexing that caused warnings in numpy >=1.15 have been resolved.

The 2d inverse stationary wavelet transform, iswt2, now supports non-square inputs (an unnecessary check for square inputs was removed).

Wavelet packets no longer convert float32 to float64 upon assignment to nodes.

Doctests have been updated to also work with NumPy >= 1.14,

Indexing conventions have been updated to avoid FutureWarnings in NumPy 1.15.

Other changes#

Python 3.7 is now officially supported.


  • 0-tree +

  • Jacopo Antonello +

  • Matthew Brett +

  • Saket Choudhary +

  • Michael V. DePalatis +

  • Daniel Goertzen +

  • Ralf Gommers

  • Mark Harfouche +

  • John Kirkham +

  • Dawid Laszuk +

  • Gregory R. Lee

  • Michel Pelletier +

  • Balint Reczey +

  • SylvainLan +

  • Daniele Tricoli

  • Kai Wohlfahrt

A total of 16 people contributed to this release. People with a “+” by their names contributed a patch for the first time. This list of names is automatically generated, and may not be fully complete.

Issues closed for v1.0.0#

The following 15 issues were closed for this release.

  • #405: New warning appearing

  • #397: Make pip install work if numpy is not yet installed

  • #396: Allow more levels in wavedec

  • #386: Improve documentation for cwt

  • #396: Allow more levels in wavedec

  • #368: Bug in ISWT2 for non-rectangular arrays

  • #363: Crash threading swt2

  • #357: reconstruction from array_to_coeff and waverec

  • #352: FYI: PyWavelet does not correctly declare dependency…

  • #338: upcoef - TypeError: No matching signature found

  • #335: Build issue: PyWavelets does not install from sdist

  • #333: user-friendly error messages regarding discrete vs. continuous…

  • #326: Allow complex dtype of input

  • #316: Test fail in some architectures

  • #312: Documentation should suggest using the default conda channel

  • #308: incorporate bandwidths into CWT wavelet names for families cmor,…

  • #306: dwt_max_levels not enough documentation

  • #302: Can’t remove cA and then reconstruct

  • #290: idwtn should treat coefficients set to None as zeros

  • #288: RuntimeErrors and segfaults from swt2() in threaded environments

Pull requests for v1.0.0#

A total of 53 pull requests were merged for this release.

  • #248: DOC: sync PyWavelets main descriptions.

  • #249: Add pyqtgraph demo for plotting wavelets

  • #254: DOC: fix rendering of wavelist docstring

  • #255: ENH: improve iswt performance

  • #256: ENH: add iswtn (n-dimensional inverse SWT)

  • #257: s/addional/additional/

  • #260: TST: test OS X build on TravisCI. Closes gh-75.

  • #262: avoid some compiler warnings

  • #263: MAINT: better exception message for Wavelet(‘continuous_familyname’)

  • #264: add ASV (continued)

  • #265: MAINT: fix more compiler warnings

  • #269: allow string input in dwt_max_level

  • #270: DOC: update ISWT documentation

  • #272: allow separate wavelet/mode for each axis in routines based on…

  • #273: fix non-integer index error

  • #275: ENH: use single precision routines for half-precision inputs

  • #276: update wp_scalogram demo work with matplotlib 2.0

  • #285: Fix spelling typo

  • #286: MAINT: Package the license file

  • #291: idwtn should allow coefficients to be set as None

  • #292: MAINT: ensure tests are included in wheels

  • #294: FIX: shape adjustment in waverec should not assume a transform…

  • #299: DOC: update outdated scipy-user email address

  • #300: ENH: compiling with C99 support (non-MSVC only)

  • #303: DOC: better document how to handle omitted coefficients in multilevel…

  • #309: Document how max levels are determined for multilevel DWT and…

  • #310: parse CWT wavelet names for parameters

  • #314: TST: Explicitly align data records in test_byte_offset()

  • #317: TST: specify rtol and atol for assert_allclose calls in test_swt_decomposition

  • #320: Suggest using default conda channel to install

  • #321: BLD: add pyproject.toml file (PEP 518 support).

  • #322: support soft thresholding of complex valued data

  • #331: Rename to CONTRIBUTING.rst

  • #337: provide a more helpful error message for wrong wavelet type

  • #339: check for wrong number of dimensions in upcoef and downcoef

  • #340: DOC: fix broken link to Airspeed Velocity documentation

  • #344: force legacy numpy repr for doctests

  • #349: test case for CWT with complex input

  • #350: better document the size requirements for swt/swt2/swtn

  • #351: Add two new antisymmetric edge modes

  • #353: DOC: add citation info to the front page of the docs.

  • #354: add firm (semi-soft) and non-negative garotte thresholding

  • #355: swt(): inference of level=None to depend on axis

  • #356: fix: default level in wavedec2 and wavedecn can be too conservative

  • #360: fix Continuous spelling

  • #361: AttributeError when using coeffs_to_array

  • #362: Fix spelling of continuous globally

  • #364: DOC: Explicitly print wavelet name for invalid wavelets

  • #367: fix segfault related to parallel SWT

  • #369: remove iswt2’s restriction on non-square inputs

  • #376: add common 1d synthetic signals

  • #377: minor update to demo_signals

  • #378: numpy: 1.15 multiindexing warning. targeted fix

  • #380: BLD: fix doc build on ReadTheDocs, need matplotlib for plots…

  • #381: Fix corner case for small scales in CWT

  • #382: avoid FutureWarnings related to multiindexing in Numpy1.15

  • #383: adding Community guidelines

  • #384: swap swt2 coefficient order (and remove FutureWarnings)

  • #387: improve CWT docs

  • #390: MAINT: update Python version support. Closes gh-385.

  • #391: fix broken link in documentation

  • #392: do not force float64 dtype on assignment to Node, Node2D

  • #398: MAINT: update .gitignore for files generated during build.

  • #401: Fix failing numpy 1.9.3 build on Travis CI

  • #403: Change ValueError to UserWarning when level is > dwt_max_level

  • #404: BLD: fix ReadTheDocs build. Outdated NumPy gave a conflict with MPL.

  • #410: DOC: rewrite docs front page

  • #413: add disclaimer