def __init__(self,
space,
wavelet,
nlevels,
variant,
pad_mode='constant',
pad_const=0,
impl='pywt'):
"""Initialize a new instance.
Parameters
----------
space : `DiscreteLp`
Domain of the forward wavelet transform (the "image domain").
In the case of ``variant in ('inverse', 'adjoint')``, this
space is the range of the operator.
wavelet : string or `pywt.Wavelet`
Specification of the wavelet to be used in the transform.
If a string is given, it is converted to a `pywt.Wavelet`.
Use `pywt.wavelist` to get a list of available wavelets.
Possible wavelet families are:
``'haar'``: Haar
``'db'``: Daubechies
``'sym'``: Symlets
``'coif'``: Coiflets
``'bior'``: Biorthogonal
``'rbio'``: Reverse biorthogonal
``'dmey'``: Discrete FIR approximation of the Meyer wavelet
variant : {'forward', 'inverse', 'adjoint'}
Wavelet transform variant to be created.
nlevels : positive int, optional
Number of scaling levels to be used in the decomposition. The
maximum number of levels can be calculated with
`pywt.dwt_max_level`.
Default: Use maximum number of levels.
pad_mode : string, optional
Method to be used to extend the signal.
``'constant'``: Fill with ``pad_const``.
``'symmetric'``: Reflect at the boundaries, not doubling the
outmost values.
``'periodic'``: Fill in values from the other side, keeping
the order.
``'order0'``: Extend constantly with the outmost values
(ensures continuity).
``'order1'``: Extend with constant slope (ensures continuity of
the first derivative). This requires at least 2 values along
each axis where padding is applied.
``'pywt_per'``: like ``'periodic'``-padding but gives the smallest
possible number of decomposition coefficients.
Only available with ``impl='pywt'``, See `pywt.MODES.modes`.
pad_const : float, optional
Constant value to use if ``pad_mode == 'constant'``. Ignored
otherwise. Constants other than 0 are not supported by the
``pywt`` back-end.
impl : {'pywt'}, optional
Back-end for the wavelet transform.
"""
if not isinstance(space, DiscreteLp):
raise TypeError('`space` {!r} is not a `DiscreteLp` instance.'
''.format(space))
if nlevels is None:
nlevels = pywt_max_nlevels(space.shape, wavelet)
self.__nlevels, nlevels_in = int(nlevels), nlevels
if self.nlevels != nlevels_in:
raise ValueError('`nlevels` must be integer, got {}'
''.format(nlevels_in))
self.__impl, impl_in = str(impl).lower(), impl
if self.impl not in _SUPPORTED_WAVELET_IMPLS:
raise ValueError("`impl` '{}' not supported".format(impl_in))
self.__wavelet = getattr(wavelet, 'name', str(wavelet).lower())
self.__pad_mode = str(pad_mode).lower()
self.__pad_const = space.field.element(pad_const)
if self.impl == 'pywt':
self.pywt_pad_mode = pywt_pad_mode(pad_mode, pad_const)
self.pywt_wavelet = pywt_wavelet(self.wavelet)
coeff_size = pywt_flat_coeff_size(space.shape, wavelet,
self.nlevels, self.pywt_pad_mode)
coeff_space = space.dspace_type(coeff_size, dtype=space.dtype)
else:
raise RuntimeError("bad `impl` '{}'".format(self.impl))
variant, variant_in = str(variant).lower(), variant
if variant not in ('forward', 'inverse', 'adjoint'):
raise ValueError("`variant` '{}' not understood"
"".format(variant_in))
self.__variant = variant
if variant == 'forward':
super().__init__(domain=space, range=coeff_space, linear=True)
else:
super().__init__(domain=coeff_space, range=space, linear=True)
def __init__(self, space, wavelet, nlevels, variant, pad_mode='constant',
pad_const=0, impl='pywt'):
"""Initialize a new instance.
Parameters
----------
space : `DiscreteLp`
Domain of the forward wavelet transform (the "image domain").
In the case of ``variant in ('inverse', 'adjoint')``, this
space is the range of the operator.
wavelet : string or `pywt.Wavelet`
Specification of the wavelet to be used in the transform.
If a string is given, it is converted to a `pywt.Wavelet`.
Use `pywt.wavelist` to get a list of available wavelets.
Possible wavelet families are:
``'haar'``: Haar
``'db'``: Daubechies
``'sym'``: Symlets
``'coif'``: Coiflets
``'bior'``: Biorthogonal
``'rbio'``: Reverse biorthogonal
``'dmey'``: Discrete FIR approximation of the Meyer wavelet
nlevels : positive int
Number of scaling levels to be used in the decomposition. The
maximum number of levels can be calculated with
`pywt.dwt_max_level`.
variant : {'forward', 'inverse', 'adjoint'}
Wavelet transform variant to be created.
pad_mode : string, optional
Method to be used to extend the signal.
``'constant'``: Fill with ``pad_const``.
``'symmetric'``: Reflect at the boundaries, not doubling the
outmost values.
``'periodic'``: Fill in values from the other side, keeping
the order.
``'order0'``: Extend constantly with the outmost values
(ensures continuity).
``'order1'``: Extend with constant slope (ensures continuity of
the first derivative). This requires at least 2 values along
each axis where padding is applied.
``'pywt_per'``: like ``'periodic'``-padding but gives the smallest
possible number of decomposition coefficients.
Only available with ``impl='pywt'``, See `pywt.MODES.modes`.
pad_const : float, optional
Constant value to use if ``pad_mode == 'constant'``. Ignored
otherwise. Constants other than 0 are not supported by the
``pywt`` back-end.
impl : {'pywt'}, optional
Back-end for the wavelet transform.
"""
if not isinstance(space, DiscreteLp):
raise TypeError('`space` {!r} is not a `DiscreteLp` instance.'
''.format(space))
self.__nlevels, nlevels_in = int(nlevels), nlevels
if self.nlevels != nlevels_in:
raise ValueError('`nlevels` must be integer, got {}'
''.format(nlevels_in))
self.__impl, impl_in = str(impl).lower(), impl
if self.impl not in _SUPPORTED_WAVELET_IMPLS:
raise ValueError("`impl` '{}' not supported".format(impl_in))
self.__wavelet = getattr(wavelet, 'name', str(wavelet).lower())
self.__pad_mode = str(pad_mode).lower()
self.__pad_const = space.field.element(pad_const)
if self.impl == 'pywt':
self.pywt_pad_mode = pywt_pad_mode(pad_mode, pad_const)
self.pywt_wavelet = pywt_wavelet(self.wavelet)
coeff_size = pywt_flat_coeff_size(space.shape, wavelet,
self.nlevels, self.pywt_pad_mode)
coeff_space = space.dspace_type(coeff_size, dtype=space.dtype)
else:
raise RuntimeError("bad `impl` '{}'".format(self.impl))
variant, variant_in = str(variant).lower(), variant
if variant not in ('forward', 'inverse', 'adjoint'):
raise ValueError("`variant` '{}' not understood"
"".format(variant_in))
self.__variant = variant
if variant == 'forward':
super().__init__(domain=space, range=coeff_space, linear=True)
else:
super().__init__(domain=coeff_space, range=space, linear=True)