chain_operator.py 4.87 KB
Newer Older
Martin Reinecke's avatar
Martin Reinecke committed
1 2 3 4 5 6 7 8 9 10 11 12 13
# 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/>.
#
14
# Copyright(C) 2013-2018 Max-Planck-Society
Martin Reinecke's avatar
Martin Reinecke committed
15 16 17 18
#
# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik
# and financially supported by the Studienstiftung des deutschen Volkes.

19
import numpy as np
Martin Reinecke's avatar
Martin Reinecke committed
20 21 22 23
from .linear_operator import LinearOperator


class ChainOperator(LinearOperator):
Martin Reinecke's avatar
Martin Reinecke committed
24 25
    """Class representing chains of operators."""

Martin Reinecke's avatar
Martin Reinecke committed
26 27 28
    def __init__(self, ops, _callingfrommake=False):
        if not _callingfrommake:
            raise NotImplementedError
Martin Reinecke's avatar
Martin Reinecke committed
29
        super(ChainOperator, self).__init__()
Martin Reinecke's avatar
Martin Reinecke committed
30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55
        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:
56 57
            if (isinstance(op, ScalingOperator) and
                    not np.issubdtype(type(op._factor), np.complexfloating)):
Martin Reinecke's avatar
Martin Reinecke committed
58 59 60 61 62 63 64
                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):
Martin Reinecke's avatar
Martin Reinecke committed
65
                    opsnew[i] = opsnew[i]._scale(fct)
Martin Reinecke's avatar
Martin Reinecke committed
66 67
                    fct = 1.
                    break
Martin Reinecke's avatar
bug fix  
Martin Reinecke committed
68
        if fct != 1 or len(opsnew) == 0:
Martin Reinecke's avatar
Martin Reinecke committed
69 70 71 72 73 74 75 76
            # 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
77
                    isinstance(op, DiagonalOperator)):
Martin Reinecke's avatar
Martin Reinecke committed
78
                opsnew[-1] = opsnew[-1]._combine_prod(op)
Martin Reinecke's avatar
Martin Reinecke committed
79 80 81
            else:
                opsnew.append(op)
        ops = opsnew
Martin Reinecke's avatar
Martin Reinecke committed
82 83 84 85 86 87 88 89 90 91 92
        # 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
Martin Reinecke's avatar
Martin Reinecke committed
93 94 95 96
        return ops

    @staticmethod
    def make(ops):
Martin Reinecke's avatar
Martin Reinecke committed
97
        """Build a ChainOperator (or something simpler if possible),
98 99 100 101 102 103 104
        a sequence of concatenated LinearOperators.

        Parameters
        ----------
        ops: list of LinearOperator
            Individual operators of the chain.
        """
Martin Reinecke's avatar
Martin Reinecke committed
105
        ops = tuple(ops)
Martin Reinecke's avatar
bug fix  
Martin Reinecke committed
106 107
        if len(ops) == 0:
            raise ValueError("ops is empty")
Martin Reinecke's avatar
Martin Reinecke committed
108 109 110 111
        ops = ChainOperator.simplify(ops)
        if len(ops) == 1:
            return ops[0]
        return ChainOperator(ops, _callingfrommake=True)
Martin Reinecke's avatar
Martin Reinecke committed
112 113 114

    @property
    def domain(self):
Martin Reinecke's avatar
Martin Reinecke committed
115
        return self._ops[-1].domain
Martin Reinecke's avatar
Martin Reinecke committed
116 117 118

    @property
    def target(self):
Martin Reinecke's avatar
Martin Reinecke committed
119
        return self._ops[0].target
Martin Reinecke's avatar
Martin Reinecke committed
120

121 122 123 124 125
    def _flip_modes(self, trafo):
        ADJ = self.ADJOINT_BIT
        INV = self.INVERSE_BIT

        if trafo == 0:
Martin Reinecke's avatar
Martin Reinecke committed
126
            return self
127 128
        if trafo == ADJ or trafo == INV:
            return self.make([op._flip_modes(trafo)
Martin Reinecke's avatar
Martin Reinecke committed
129
                              for op in reversed(self._ops)])
130 131 132
        if trafo == ADJ | INV:
            return self.make([op._flip_modes(trafo) for op in self._ops])
        raise ValueError("invalid operator transformation")
Martin Reinecke's avatar
Martin Reinecke committed
133

Martin Reinecke's avatar
Martin Reinecke committed
134 135
    @property
    def capability(self):
Martin Reinecke's avatar
Martin Reinecke committed
136
        return self._capability
Martin Reinecke's avatar
Martin Reinecke committed
137 138 139

    def apply(self, x, mode):
        self._check_mode(mode)
Martin Reinecke's avatar
Martin Reinecke committed
140 141 142 143
        t_ops = self._ops if mode & self._backwards else reversed(self._ops)
        for op in t_ops:
            x = op.apply(x, mode)
        return x