==============================
PyWavelets 0.5.0 Release Notes
==============================

.. |MATLAB|  unicode:: MATLAB U+02122 .. with trademark sign

.. contents::

PyWavelets is a Python toolbox implementing both discrete and continuous
wavelet transforms (mathematical time-frequency transforms) with a wide range
of built-in wavelets.  C/Cython are used for the low-level routines, enabling
high performance.  Key Features of PyWavelets are:

  * 1D, 2D and nD Forward and Inverse Discrete Wavelet Transform (DWT and IDWT)
  * 1D, 2D and nD Multilevel DWT and IDWT
  * 1D and 2D Forward and Inverse Stationary Wavelet Transform
  * 1D and 2D Wavelet Packet decomposition and reconstruction
  * 1D Continuous Wavelet Transform
  * When multiple valid implementations are available, we have chosen to maintain consistency with |MATLAB|'s Wavelet Toolbox.

PyWavelets 0.5.0 is the culmination of 1 year of work.  In addition to
several new features, substantial refactoring of the underlying C and Cython
code have been made.

This release requires Python 2.6, 2.7 or 3.3-3.5 and NumPy 1.9.1 or greater.
This will be the final release supporting Python 2.6 and 3.3.

Highlights of this release include:

- 1D continuous wavelet transforms
- new discrete wavelets added (additional Debauchies and Coiflet wavelets)
- new 'reflect' extension mode for discrete wavelet transforms
- faster performance for multilevel forward stationary wavelet transforms (SWT)
- n-dimensional support added to forward SWT
- routines to convert multilevel DWT coefficients to and from a single array
- axis support for multilevel DWT
- substantial refactoring/reorganization of the underlying C and Cython code


New features
============

1D Continuous Wavelet Transforms
-------------------------------
A wide range of continuous wavelets are now available.  These include the
following:

- Gaussian wavelets (``gaus1``...``gaus8``)
- Mexican hat wavelet (``mexh``)
- Morlet wavelet (``morl``)
- Complex Gaussian wavelets (``cgau1``...``cgau8``)
- Shannon wavelet (``shan``)
- Frequency B-Spline wavelet (``fbsp``)
- Complex Morlet wavelet (``cmor``)

Also, see the new CWT-related demo: demo/cwt_analysis.py

New discrete wavelets
---------------------
Additional Debauchies wavelets (``db20``...``db38``) and Coiflets
(``coif6``...``coif17``) have been added.

New extension mode: reflect
---------------------------
Discrete wavelet transforms support a new extension mode, ``reflect``.  This
mode pads an array symmetrically, but without repeating the edge value.  As an
example::

     pad      array      pad
    4 3 2 | 1 2 3 4 5 | 4 3 2

This differs from ``symmetric``, which repeats the values at the boundaries::

     pad      array      pad
    3 2 1 | 1 2 3 4 5 | 5 4 3

Multilevel DWT Coefficient Handling
-----------------------------------
New routines to convert the coefficients returned by multilevel DWT routines
to and from a single n-dimensional array have been added.
``pywt.coeffs_to_array`` concatenates the output of ``wavedec``, ``wavedec2``
or ``wavedecn`` into a single numpy array.  ``pywt.array_to_coeffs`` can be
used to transform back from a single coefficient array to a format appropriate
for ``waverec``, ``waverec2`` or ``waverecn``.

More C function calls release the GIL
-------------------------------------
Cython code calling the wavelet filtering routines (DWT and SWT) now releases
the global interpreter lock (GIL) where possible.  A potential use case is in
speeding up the batch computation of several large DWTs using multi-threading
(e.g. via concurrent.futures).

Multilevel wavelet transforms along specific axes
-------------------------------------------------
The axis specific transform support introduced in the prior release was
extended to the multilevel DWT transforms.  All ``wavedec*`` and ``waverec*``
routines have a new `axis` (1D) or `axes` (2D, nD) keyword argument.  If
unspecified the default behaviour is to transform all axes of the input.

Faster multilevel stationary wavelet transforms
-----------------------------------------------
Stationary wavelet transforms are now faster when the number of levels is
greater than one.  The improvement can be very large (multiple orders of
magnitude) for transforms with a large number of levels.


Deprecated features
===================


Backwards incompatible changes
==============================

A FutureWarning was added to ``swt2`` and ``iswt2`` to warn about a pending
backwards incompatible change to the order of the coefficients in the list
returned by these routines.  The actual change will not occur until the next
release. Transform coefficients will be returned in descending rather than
ascending order.  This change is being made for consistency with all other
existing multi-level transforms in PyWavelets.

Bugs Fixed
==========

``demo/image_blender.py`` was updated to support the new api of Pillow 3.x

A bug related to size of assumed ``size_t`` on some platforms/compilers
(e.g. Windows with mingw64) was fixed.

Fix to memory leak in ``(i)dwt_axis``

Fix to a performance regression in ``idwt`` and ``iswt`` that was introduced
in v0.4.0.

Fixed a bug in ``dwtn`` and ``idwtn`` for data with complex dtype when
``axes != None``.

Other changes
=============

The minimum supported numpy version has been increased to 1.9.1.

Test coverage (including for the Cython and C code) via
`Codecov <https://codecov.io/>`_ was added and the overall test coverage has
been improved.

A substantial overhaul of the C extension code has been performed.  Custom
templating is no longer used.  The intention is to make this code easier to
maintain and expand in the future.

The Cython code has been split out into a multiple files to hopefully make
relevant portions of the wrappers easier to find for future developers.

``setup.py`` now relies on setuptools in all cases (rather than distutils).

Authors
=======

* Jonathan Dan +
* Ralf Gommers
* David Menéndez Hurtado
* Gregory R. Lee
* Holger Nahrstaedt +
* Daniel M. Pelt +
* Alexandre Saint +
* Scott Sievert +
* Kai Wohlfahrt
* Frank Yu +

A total of 10 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 v0.5.0
------------------------

- `#48 <https://github.com/PyWavelets/pywt/issues/48>`__: Continuous wavelet transform?
- `#127 <https://github.com/PyWavelets/pywt/issues/127>`__: Reorganize _pywt
- `#160 <https://github.com/PyWavelets/pywt/issues/160>`__: Appveyor failing on recent PRs
- `#163 <https://github.com/PyWavelets/pywt/issues/163>`__: Set up coveralls
- `#166 <https://github.com/PyWavelets/pywt/issues/166>`__: Wavelet coefficients to single array (and vice versa?)
- `#177 <https://github.com/PyWavelets/pywt/issues/177>`__: Fail to install pywt due to the use of index_t which conflict with the definition in /usr/include/sys/types.h on smartos system(open solaris like system)
- `#180 <https://github.com/PyWavelets/pywt/issues/180>`__: Memory leak
- `#187 <https://github.com/PyWavelets/pywt/issues/187>`__: 'reflect' signal extension mode
- `#189 <https://github.com/PyWavelets/pywt/issues/189>`__: bump minimum numpy version?
- `#191 <https://github.com/PyWavelets/pywt/issues/191>`__: Upgrade removed Pillow methods
- `#196 <https://github.com/PyWavelets/pywt/issues/196>`__: building in-place for development.
- `#200 <https://github.com/PyWavelets/pywt/issues/200>`__: swt implementation is considerably slower than MATLAB
- `#209 <https://github.com/PyWavelets/pywt/issues/209>`__: broken doctests
- `#210 <https://github.com/PyWavelets/pywt/issues/210>`__: Run doctests in CI setup
- `#211 <https://github.com/PyWavelets/pywt/issues/211>`__: Typo in iswt documentation
- `#217 <https://github.com/PyWavelets/pywt/issues/217>`__: `blank_discrete_wavelet` does not properly initialize some properties
- `#231 <https://github.com/PyWavelets/pywt/issues/231>`__: I can't compile pywt


Pull requests for v0.5.0
------------------------

- `#148 <https://github.com/PyWavelets/pywt/pull/148>`__: Reorganize C v2
- `#161 <https://github.com/PyWavelets/pywt/pull/161>`__: Remove numpy distutils
- `#162 <https://github.com/PyWavelets/pywt/pull/162>`__: fix: iswt/idwt performance regression
- `#164 <https://github.com/PyWavelets/pywt/pull/164>`__: Improved coefficients for db and coif
- `#167 <https://github.com/PyWavelets/pywt/pull/167>`__: Add coverage (codecov.io)
- `#168 <https://github.com/PyWavelets/pywt/pull/168>`__: convert transform coefficients to and from a single n-dimensional array
- `#169 <https://github.com/PyWavelets/pywt/pull/169>`__: Remove templating
- `#170 <https://github.com/PyWavelets/pywt/pull/170>`__: :Always install new pip on Appveyor
- `#172 <https://github.com/PyWavelets/pywt/pull/172>`__: Adding of missing wavelets from the matlab list
- `#178 <https://github.com/PyWavelets/pywt/pull/178>`__: use Index_t instead of index_t
- `#179 <https://github.com/PyWavelets/pywt/pull/179>`__: add axis/axes support to multilevel discrete wavelet transforms
- `#181 <https://github.com/PyWavelets/pywt/pull/181>`__: Fix memory leak
- `#182 <https://github.com/PyWavelets/pywt/pull/182>`__: improve test coverage for _multidim.py and _multilevel.py
- `#183 <https://github.com/PyWavelets/pywt/pull/183>`__: improve coverage for _dwt.py
- `#184 <https://github.com/PyWavelets/pywt/pull/184>`__: fix corner case in coeffs_to_array
- `#188 <https://github.com/PyWavelets/pywt/pull/188>`__: Drop GIL in c_wt calls
- `#190 <https://github.com/PyWavelets/pywt/pull/190>`__: bump minimum numpy to 1.9
- `#192 <https://github.com/PyWavelets/pywt/pull/192>`__: Upgrade to Pillow>=3 api
- `#193 <https://github.com/PyWavelets/pywt/pull/193>`__: ENH: add 'reflect' extension mode
- `#197 <https://github.com/PyWavelets/pywt/pull/197>`__: BLD: fix "python setup.py develop". Closes gh-196
- `#198 <https://github.com/PyWavelets/pywt/pull/198>`__: Choose clz* based on SIZE_MAX
- `#201 <https://github.com/PyWavelets/pywt/pull/201>`__: speedup multi-level swt
- `#205 <https://github.com/PyWavelets/pywt/pull/205>`__: fix dwtn/idwtn with axes != None and complex data
- `#206 <https://github.com/PyWavelets/pywt/pull/206>`__:  DOC: correct typo in iswt docstring
- `#207 <https://github.com/PyWavelets/pywt/pull/207>`__:  minor documentation updates
- `#208 <https://github.com/PyWavelets/pywt/pull/208>`__: document coeff_to_array and array_to_coeff
- `#214 <https://github.com/PyWavelets/pywt/pull/214>`__: FIX: update several doctests to reflect the new wavelets added
- `#218 <https://github.com/PyWavelets/pywt/pull/218>`__: FIX: initialize all properties of a blank discrete wavelet
- `#219 <https://github.com/PyWavelets/pywt/pull/219>`__: document coordinate conventions for 2D DWT routines.
- `#220 <https://github.com/PyWavelets/pywt/pull/220>`__: Run doctests on TravisCI
- `#221 <https://github.com/PyWavelets/pywt/pull/221>`__: Documentation for cwt and ContinuousWavelet
- `#222 <https://github.com/PyWavelets/pywt/pull/222>`__: consistent use of double backticks in docs
- `#223 <https://github.com/PyWavelets/pywt/pull/223>`__: add FutureWarning about swt2 coefficient order
- `#224 <https://github.com/PyWavelets/pywt/pull/224>`__: n-dimensional stationary wavelet transform (swtn) and axis support in swt, swt2
- `#225 <https://github.com/PyWavelets/pywt/pull/225>`__: BUG: fix breakage on 32-bit Python.
- `#226 <https://github.com/PyWavelets/pywt/pull/226>`__: DOC: update Copyright statements.
- `#227 <https://github.com/PyWavelets/pywt/pull/227>`__: ENH: add kind keyword to wavelist()
- `#228 <https://github.com/PyWavelets/pywt/pull/228>`__: MAINT: avoid using a builtin as variable name in qmf().
- `#229 <https://github.com/PyWavelets/pywt/pull/229>`__: DOC: add swtn, iswt, iswt2 to the API documentation
- `#230 <https://github.com/PyWavelets/pywt/pull/230>`__: add demo of batch processing via concurrent.futures
- `#234 <https://github.com/PyWavelets/pywt/pull/234>`__: ENH: coeffs_to_array supports axes argument as recently added to wavedec*
- `#236 <https://github.com/PyWavelets/pywt/pull/236>`__: BLD: raise an ImportError if Cython should be installed but isn't.
