simple_linear_operators.py 7.16 KB
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# 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/>.
#
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# Copyright(C) 2013-2019 Max-Planck-Society
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#
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# NIFTy is being developed at the Max-Planck-Institut fuer Astrophysik.
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from ..domain_tuple import DomainTuple
from ..domains.unstructured_domain import UnstructuredDomain
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from ..field import Field
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from ..multi_domain import MultiDomain
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from ..multi_field import MultiField
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from .endomorphic_operator import EndomorphicOperator
from .linear_operator import LinearOperator
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class VdotOperator(LinearOperator):
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    """Operator computing the scalar product of its input with a given Field.

    Parameters
    ----------
    field : Field/MultiField
        The field used to build the scalar product with the operator input
    """
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    def __init__(self, field):
        self._field = field
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        self._domain = field.domain
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        self._target = DomainTuple.scalar_domain()
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        self._capability = self.TIMES | self.ADJOINT_TIMES
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    def apply(self, x, mode):
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        self._check_mode(mode)
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        if mode == self.TIMES:
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            return Field.scalar(self._field.vdot(x))
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        return self._field*x.local_data[()]
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class ConjugationOperator(EndomorphicOperator):
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    """Operator computing the complex conjugate of its input."""
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    def __init__(self, domain):
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        self._domain = DomainTuple.make(domain)
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        self._capability = self._all_ops
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    def apply(self, x, mode):
        self._check_input(x, mode)
        return x.conjugate()


class Realizer(EndomorphicOperator):
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    """Operator returning the real component of its input."""
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    def __init__(self, domain):
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        self._domain = DomainTuple.make(domain)
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        self._capability = self.TIMES | self.ADJOINT_TIMES
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    def apply(self, x, mode):
        self._check_input(x, mode)
        return x.real
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class FieldAdapter(LinearOperator):
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    """Operator for conversion between Fields and MultiFields.
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    Parameters
    ----------
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    tgt : Domain, tuple of Domain, DomainTuple, dict or MultiDomain:
        If this is a Domain, tuple of Domain or DomainTuple, this will be the
        operator's target, and its domain will be a MultiDomain consisting of
        its domain with the supplied `name`
        If this is a dict or MultiDomain, everything except for `name` will
        be stripped out of it, and the result will be the operator's target.
        Its domain will then be the DomainTuple corresponding to the single
        entry in the operator's domain.
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    name : String
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        The relevant key of the MultiDomain.
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    """

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    def __init__(self, tgt, name):
        from ..sugar import makeDomain
        tmp = makeDomain(tgt)
        if isinstance(tmp, DomainTuple):
            self._target = tmp
            self._domain = MultiDomain.make({name: tmp})
        else:
            self._domain = tmp[name]
            self._target = MultiDomain.make({name: tmp[name]})
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        self._capability = self.TIMES | self.ADJOINT_TIMES
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    def apply(self, x, mode):
        self._check_input(x, mode)
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        if isinstance(x, MultiField):
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            return x.values()[0]
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        else:
            return MultiField(self._tgt(mode), (x,))

    def __repr__(self):
        key = self.domain.keys()[0]
        return 'FieldAdapter: {}'.format(key)


def ducktape(left, right, name):
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    """Convenience function for computing an adapter between two operators.

    Parameters
    ----------
    left : None, Operator, or Domainoid
        Something describing the input domain of the left operator.
        If `left` is an `Operator`, its domain is used as `left`.

    right : None, Operator, or Domainoid
        Something describing the target domain of the right operator.
        If `right` is an `Operator`, its target is used as `right`.

    name : string
        The component of the `MultiDomain` that will be extracted/inserted

    Notes
    -----
    - one of the involved domains must be a `DomainTuple`, the other a
      `MultiDomain`.
    - `left` and `right` must not be both `None`, but one of them can (and
      probably should) be `None`. In this case, the missing information is
      inferred.

    Returns
    -------
    FieldAdapter : an adapter operator converting between the two (possibly
                   partially inferred) domains.
    """
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    from ..sugar import makeDomain
    from .operator import Operator
    if left is None:  # need to infer left from right
        if isinstance(right, Operator):
            right = right.target
        elif right is not None:
            right = makeDomain(right)
        if isinstance(right, MultiDomain):
            left = right[name]
        else:
            left = MultiDomain.make({name: right})
    else:
        if isinstance(left, Operator):
            left = left.domain
        else:
            left = makeDomain(left)
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    return FieldAdapter(left, name)
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class GeometryRemover(LinearOperator):
    """Operator which transforms between a structured and an unstructured
    domain.

    Parameters
    ----------
    domain: Domain, tuple of Domain, or DomainTuple:
        the full input domain of the operator.
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    space: int, optional
        The index of the subdomain on which the operator should act
        If None, it acts on all spaces
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    Notes
    -----
    The operator will convert every sub-domain of its input domain to an
    UnstructuredDomain with the same shape. No weighting by volume factors
    is carried out.
    """

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    def __init__(self, domain, space=None):
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        self._domain = DomainTuple.make(domain)
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        if space is not None:
            tgt = [dom for dom in self._domain]
            tgt[space] = UnstructuredDomain(self._domain[space].shape)
        else:
            tgt = [UnstructuredDomain(dom.shape) for dom in self._domain]
        self._target = DomainTuple.make(tgt)
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        self._capability = self.TIMES | self.ADJOINT_TIMES
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    def apply(self, x, mode):
        self._check_input(x, mode)
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        return x.cast_domain(self._tgt(mode))
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class NullOperator(LinearOperator):
    """Operator corresponding to a matrix of all zeros.

    Parameters
    ----------
    domain : DomainTuple or MultiDomain
        input domain
    target : DomainTuple or MultiDomain
        output domain
    """

    def __init__(self, domain, target):
        from ..sugar import makeDomain
        self._domain = makeDomain(domain)
        self._target = makeDomain(target)
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        self._capability = self.TIMES | self.ADJOINT_TIMES
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    @staticmethod
    def _nullfield(dom):
        if isinstance(dom, DomainTuple):
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            return Field(dom, 0)
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        else:
            return MultiField.full(dom, 0)

    def apply(self, x, mode):
        self._check_input(x, mode)
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        return self._nullfield(self._tgt(mode))