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.. _reg-modes:
.. currentmodule:: pywt
Signal Extension Modes
======================
Import :mod:`pywt` first
>>> import pywt
>>> def format_array(a):
... """Consistent array representation across different systems"""
... import numpy
... a = numpy.where(numpy.abs(a) < 1e-5, 0, a)
... return numpy.array2string(a, precision=5, separator=' ', suppress_small=True)
List of available signal extension :ref:`modes <Modes>`:
>>> print(pywt.Modes.modes)
['zero', 'constant', 'symmetric', 'periodic', 'smooth', 'periodization', 'reflect', 'antisymmetric', 'antireflect']
Invalid mode name should rise a :exc:`ValueError`:
>>> pywt.dwt([1,2,3,4], 'db2', 'invalid')
Traceback (most recent call last):
...
ValueError: Unknown mode name 'invalid'.
You can also refer to modes via :ref:`Modes <Modes>` class attributes:
>>> x = [1, 2, 1, 5, -1, 8, 4, 6]
>>> for mode_name in ['zero', 'constant', 'symmetric', 'reflect', 'periodic', 'smooth', 'periodization']:
... mode = getattr(pywt.Modes, mode_name)
... cA, cD = pywt.dwt(x, 'db2', mode)
... print("Mode: %d (%s)" % (mode, mode_name))
Mode: 0 (zero)
Mode: 2 (constant)
Mode: 1 (symmetric)
Mode: 6 (reflect)
Mode: 4 (periodic)
Mode: 3 (smooth)
Mode: 5 (periodization)
The default mode is :ref:`symmetric <Modes.symmetric>`:
>>> cA, cD = pywt.dwt(x, 'db2')
>>> print(cA)
[ 1.76776695 1.73309178 3.40612438 6.32928585 7.77817459]
>>> print(cD)
[-0.61237244 -2.15599552 -5.95034847 -1.21545369 1.22474487]
>>> print(pywt.idwt(cA, cD, 'db2'))
[ 1. 2. 1. 5. -1. 8. 4. 6.]
And using a keyword argument:
>>> cA, cD = pywt.dwt(x, 'db2', mode='symmetric')
>>> print(cA)
[ 1.76776695 1.73309178 3.40612438 6.32928585 7.77817459]
>>> print(cD)
[-0.61237244 -2.15599552 -5.95034847 -1.21545369 1.22474487]
>>> print(pywt.idwt(cA, cD, 'db2'))
[ 1. 2. 1. 5. -1. 8. 4. 6.]
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