# 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) 2013-2018 Max-Planck-Society # # NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik # and financially supported by the Studienstiftung des deutschen Volkes. from __future__ import absolute_import, division, print_function import abc import numpy as np from ..compat import * from .domain import Domain 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. """ @abc.abstractproperty def scalar_dvol(self): """float or None : uniform cell volume, if applicable Returns the volume factors of this domain as a floating point scalar, if the volume factors are all identical, otherwise returns None. """ raise NotImplementedError @property def dvol(self): """float or numpy.ndarray(dtype=float): Volume factors 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`. """ return self.scalar_dvol @property def total_volume(self): """float : Total domain volume Returns the sum over all the domain's pixel volumes. """ tmp = self.dvol return self.size * tmp if np.isscalar(tmp) else np.sum(tmp) @abc.abstractproperty def harmonic(self): """bool : True iff this domain is a harmonic domain.""" raise NotImplementedError def get_k_length_array(self): """k vector lengths, if applicable, Returns 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): """Sorted unique k-vector lengths, if applicable. 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): """Helper for Gaussian smoothing. 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