Source code for nifty8.operators.chain_operator
# 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) 2013-2019 Max-Planck-Society
#
# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik.
from .. import utilities
from .diagonal_operator import DiagonalOperator
from .linear_operator import LinearOperator
from .scaling_operator import ScalingOperator
from .simple_linear_operators import NullOperator
[docs]
class ChainOperator(LinearOperator):
"""Class representing chains of operators.
Notes
-----
This operator has to be called using the :attr:`make` method.
"""
[docs]
def __init__(self, ops, _callingfrommake=False):
if not _callingfrommake:
raise NotImplementedError
self._ops = ops
self._capability = self._all_ops
for op in ops:
self._capability &= op.capability
self._domain = self._ops[-1].domain
self._target = self._ops[0].target
if all(callable(op.jax_expr) for op in ops):
def joined_jax_op(x):
for op in reversed(ops):
x = op.jax_expr(x)
return x
self._jax_expr = joined_jax_op
else:
self._jax_expr = None
[docs]
@staticmethod
def simplify(ops):
# verify domains
for i in range(len(ops) - 1):
utilities.check_object_identity(ops[i + 1].target, ops[i].domain)
# unpack ChainOperators
opsnew = []
for op in ops:
opsnew += op._ops if isinstance(op, ChainOperator) else [op]
ops = opsnew
# check for NullOperators
if any(isinstance(op, NullOperator) for op in ops):
ops = (NullOperator(ops[-1].domain, ops[0].target),)
# collect ScalingOperators
fct = 1.
opsnew = []
lastdom = ops[-1].domain
dtype = None
for op in ops:
if (isinstance(op, ScalingOperator) and op._factor.imag == 0):
fct *= op._factor.real
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
op = ScalingOperator(lastdom, fct)
if dtype is not None:
op.dtype = dtype
opsnew.append(op)
ops = opsnew
# 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
# combine BlockDiagonalOperators where possible
from .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
[docs]
@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)
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")
[docs]
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
[docs]
def __repr__(self):
subs = "\n".join(sub.__repr__() for sub in self._ops)
return "ChainOperator:\n" + utilities.indent(subs)
def _simplify_for_constant_input_nontrivial(self, c_inp):
from ..multi_domain import MultiDomain
if not isinstance(self._domain, MultiDomain):
return None, self
newop = None
for op in reversed(self._ops):
c_inp, t_op = op.simplify_for_constant_input(c_inp)
newop = t_op if newop is None else op(newop)
return c_inp, newop