# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see .
#
# Copyright(C) 2013-2017 Max-Planck-Society
#
# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
# and financially supported by the Studienstiftung des deutschen Volkes.
import abc
from .domain import Domain
import numpy as np
class StructuredDomain(Domain):
"""The abstract base class for all structured NIFTy domains.
An instance of a space contains information about the manifold's
geometry and enhances the functionality of Domain by methods that
are needed for power spectrum analysis and smoothing.
"""
def __init__(self):
super(StructuredDomain, self).__init__()
@abc.abstractmethod
def scalar_dvol(self):
"""Returns the volume factors of this domain as a floating
point scalar, if the volume factors are all identical, otherwise
returns None.
Returns
-------
float or None: Volume factor
"""
raise NotImplementedError
def dvol(self):
"""Returns the volume factors of this domain, either as a floating
point scalar (if the volume factors are all identical) or as a
floating point array with a shape of `self.shape`.
Returns
-------
float or numpy.ndarray(dtype=float): Volume factors
"""
return self.scalar_dvol()
def total_volume(self):
"""Returns the sum over all the domain's pixel volumes.
Returns
-------
float : sum of all pixel volume elements
"""
tmp = self.dvol()
return self.size * tmp if np.isscalar(tmp) else np.sum(tmp)
@abc.abstractproperty
def harmonic(self):
""" Returns True iff this domain is a harmonic domain."""
raise NotImplementedError
def get_k_length_array(self):
"""The length of the k vector for every pixel.
This method is only implemented for harmonic domains.
Returns
-------
Field
An array containing the k vector lengths
"""
raise NotImplementedError
def get_unique_k_lengths(self):
""" Returns an array of floats containing the unique k vector lengths
for this domain.
This method is only implemented for harmonic domains.
"""
raise NotImplementedError
def get_fft_smoothing_kernel_function(self, sigma):
"""This method returns a smoothing kernel function.
This method, which is only implemented for harmonic domains, helps
smoothing fields that live on a domain that has this domain as
its harmonic partner. The returned function multiplies field values of
a field with a zero centered Gaussian which corresponds to a
convolution with a Gaussian kernel and sigma standard deviation in
position space.
Parameters
----------
sigma : float
A real number representing a physical scale on which the smoothing
takes place. Mathematically sigma is the standard
deviation of a convolution with a normalized, zero-centered
Gaussian that takes place in position space.
Returns
-------
function (array-like -> array-like)
A smoothing operation that multiplies values with a Gaussian
kernel.
"""
raise NotImplementedError