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Martin Reinecke authoredMartin Reinecke authored
chain_operator.py 4.87 KiB
# 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 <http://www.gnu.org/licenses/>.
#
# 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.
import numpy as np
from .linear_operator import LinearOperator
class ChainOperator(LinearOperator):
"""Class representing chains of operators."""
def __init__(self, ops, _callingfrommake=False):
if not _callingfrommake:
raise NotImplementedError
super(ChainOperator, self).__init__()
self._ops = ops
self._capability = self._all_ops
for op in ops:
self._capability &= op.capability
@staticmethod
def simplify(ops):
from .scaling_operator import ScalingOperator
from .diagonal_operator import DiagonalOperator
# Step 1: verify domains
for i in range(len(ops)-1):
if ops[i+1].target != ops[i].domain:
raise ValueError("domain mismatch")
# Step 2: unpack ChainOperators
opsnew = []
for op in ops:
if isinstance(op, ChainOperator):
opsnew += op._ops
else:
opsnew.append(op)
ops = opsnew
# Step 3: collect ScalingOperators
fct = 1.
opsnew = []
lastdom = ops[-1].domain
for op in ops:
if (isinstance(op, ScalingOperator) and
not np.issubdtype(type(op._factor), np.complexfloating)):
fct *= op._factor
else:
opsnew.append(op)
if fct != 1.:
# try to absorb the factor into a DiagonalOperator
for i in range(len(opsnew)):
if isinstance(opsnew[i], DiagonalOperator):
opsnew[i] = opsnew[i]._scale(fct)
fct = 1.
break
if fct != 1 or len(opsnew) == 0:
# have to add the scaling operator at the end
opsnew.append(ScalingOperator(fct, lastdom))
ops = opsnew
# Step 4: combine DiagonalOperators where possible
opsnew = []
for op in ops:
if (len(opsnew) > 0 and
isinstance(opsnew[-1], DiagonalOperator) and
isinstance(op, DiagonalOperator)):
opsnew[-1] = opsnew[-1]._combine_prod(op)
else:
opsnew.append(op)
ops = opsnew
# Step 5: combine BlockDiagonalOperators where possible
from ..multi.block_diagonal_operator import BlockDiagonalOperator
opsnew = []
for op in ops:
if (len(opsnew) > 0 and
isinstance(opsnew[-1], BlockDiagonalOperator) and
isinstance(op, BlockDiagonalOperator)):
opsnew[-1] = opsnew[-1]._combine_chain(op)
else:
opsnew.append(op)
ops = opsnew
return ops
@staticmethod
def make(ops):
"""Build a ChainOperator (or something simpler if possible),
a sequence of concatenated LinearOperators.
Parameters
----------
ops: list of LinearOperator
Individual operators of the chain.
"""
ops = tuple(ops)
if len(ops) == 0:
raise ValueError("ops is empty")
ops = ChainOperator.simplify(ops)
if len(ops) == 1:
return ops[0]
return ChainOperator(ops, _callingfrommake=True)
@property
def domain(self):
return self._ops[-1].domain
@property
def target(self):
return self._ops[0].target
def _flip_modes(self, trafo):
ADJ = self.ADJOINT_BIT
INV = self.INVERSE_BIT
if trafo == 0:
return self
if trafo == ADJ or trafo == INV:
return self.make([op._flip_modes(trafo)
for op in reversed(self._ops)])
if trafo == ADJ | INV:
return self.make([op._flip_modes(trafo) for op in self._ops])
raise ValueError("invalid operator transformation")
@property
def capability(self):
return self._capability
def apply(self, x, mode):
self._check_mode(mode)
t_ops = self._ops if mode & self._backwards else reversed(self._ops)
for op in t_ops:
x = op.apply(x, mode)
return x