qiskit.opflow.list_ops.summed_op のソースコード

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# (C) Copyright IBM 2020, 2023.
# This code is licensed under the Apache License, Version 2.0. You may
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"""SummedOp Class"""

from typing import List, Union, cast, Dict

import numpy as np

from qiskit import QuantumCircuit
from qiskit.circuit import ParameterExpression
from qiskit.opflow.exceptions import OpflowError
from qiskit.opflow.list_ops.list_op import ListOp
from qiskit.opflow.operator_base import OperatorBase
from qiskit.utils.deprecation import deprecate_func

[ドキュメント]class SummedOp(ListOp): """Deprecated: A class for lazily representing sums of Operators. Often Operators cannot be efficiently added to one another, but may be manipulated further so that they can be later. This class holds logic to indicate that the Operators in ``oplist`` are meant to be added together, and therefore if they reach a point in which they can be, such as after evaluation or conversion to matrices, they can be reduced by addition.""" @deprecate_func( since="0.24.0", additional_msg="For code migration guidelines, visit https://qisk.it/opflow_migration.", ) def __init__( self, oplist: List[OperatorBase], coeff: Union[complex, ParameterExpression] = 1.0, abelian: bool = False, ) -> None: """ Args: oplist: The Operators being summed. coeff: A coefficient multiplying the operator abelian: Indicates whether the Operators in ``oplist`` are known to mutually commute. """ super().__init__(oplist, combo_fn=lambda x: np.sum(x, axis=0), coeff=coeff, abelian=abelian) @property def num_qubits(self) -> int: return self.oplist[0].num_qubits @property def distributive(self) -> bool: return True @property def settings(self) -> Dict: """Return settings.""" return {"oplist": self._oplist, "coeff": self._coeff, "abelian": self._abelian}
[ドキュメント] def add(self, other: OperatorBase) -> "SummedOp": """Return Operator addition of ``self`` and ``other``, overloaded by ``+``. Note: This appends ``other`` to ``self.oplist`` without checking ``other`` is already included or not. If you want to simplify them, please use :meth:`simplify`. Args: other: An ``OperatorBase`` with the same number of qubits as self, and in the same 'Operator', 'State function', or 'Measurement' category as self (i.e. the same type of underlying function). Returns: A ``SummedOp`` equivalent to the sum of self and other. """ self_new_ops = ( self.oplist if self.coeff == 1 else [op.mul(self.coeff) for op in self.oplist] ) if isinstance(other, SummedOp): other_new_ops = ( other.oplist if other.coeff == 1 else [op.mul(other.coeff) for op in other.oplist] ) else: other_new_ops = [other] return SummedOp(self_new_ops + other_new_ops)
[ドキュメント] def collapse_summands(self) -> "SummedOp": """Return Operator by simplifying duplicate operators. E.g., ``SummedOp([2 * X ^ Y, X ^ Y]).collapse_summands() -> SummedOp([3 * X ^ Y])``. Returns: A simplified ``SummedOp`` equivalent to self. """ # pylint: disable=cyclic-import from ..primitive_ops.primitive_op import PrimitiveOp oplist = [] # type: List[OperatorBase] coeffs = [] # type: List[Union[int, float, complex, ParameterExpression]] for op in self.oplist: if isinstance(op, PrimitiveOp): new_op = PrimitiveOp(op.primitive) new_coeff = op.coeff * self.coeff if new_op in oplist: index = oplist.index(new_op) coeffs[index] += new_coeff else: oplist.append(new_op) coeffs.append(new_coeff) else: if op in oplist: index = oplist.index(op) coeffs[index] += self.coeff else: oplist.append(op) coeffs.append(self.coeff) return SummedOp([op * coeff for op, coeff in zip(oplist, coeffs)])
# TODO be smarter about the fact that any two ops in oplist could be evaluated for sum.
[ドキュメント] def reduce(self) -> OperatorBase: """Try collapsing list or trees of sums. Tries to sum up duplicate operators and reduces the operators in the sum. Returns: A collapsed version of self, if possible. """ if len(self.oplist) == 0: return SummedOp([], coeff=self.coeff, abelian=self.abelian) # reduce constituents reduced_ops = sum(op.reduce() for op in self.oplist) * self.coeff # group duplicate operators if isinstance(reduced_ops, SummedOp): reduced_ops = reduced_ops.collapse_summands() # pylint: disable=cyclic-import from ..primitive_ops.pauli_sum_op import PauliSumOp if isinstance(reduced_ops, PauliSumOp): reduced_ops = reduced_ops.reduce() if isinstance(reduced_ops, SummedOp) and len(reduced_ops.oplist) == 1: return reduced_ops.oplist[0] else: return cast(OperatorBase, reduced_ops)
[ドキュメント] def to_circuit(self) -> QuantumCircuit: """Returns the quantum circuit, representing the SummedOp. In the first step, the SummedOp is converted to MatrixOp. This is straightforward for most operators, but it is not supported for operators containing parameterized PrimitiveOps (in that case, OpflowError is raised). In the next step, the MatrixOp representation of SummedOp is converted to circuit. In most cases, if the summands themselves are unitary operators, the SummedOp itself is non-unitary and can not be converted to circuit. In that case, ExtensionError is raised in the underlying modules. Returns: The circuit representation of the summed operator. Raises: OpflowError: if SummedOp can not be converted to MatrixOp (e.g. SummedOp is composed of parameterized PrimitiveOps). """ # pylint: disable=cyclic-import from ..primitive_ops.matrix_op import MatrixOp matrix_op = self.to_matrix_op() if isinstance(matrix_op, MatrixOp): return matrix_op.to_circuit() raise OpflowError( "The SummedOp can not be converted to circuit, because to_matrix_op did " "not return a MatrixOp." )
[ドキュメント] def to_matrix_op(self, massive: bool = False) -> "SummedOp": """Returns an equivalent Operator composed of only NumPy-based primitives, such as ``MatrixOp`` and ``VectorStateFn``.""" accum = self.oplist[0].to_matrix_op(massive=massive) for i in range(1, len(self.oplist)): accum += self.oplist[i].to_matrix_op(massive=massive) return cast(SummedOp, accum * self.coeff)
[ドキュメント] def to_pauli_op(self, massive: bool = False) -> "SummedOp": # pylint: disable=cyclic-import from ..state_fns.state_fn import StateFn pauli_sum = SummedOp( [ op.to_pauli_op(massive=massive) # type: ignore if not isinstance(op, StateFn) else op for op in self.oplist ], coeff=self.coeff, abelian=self.abelian, ).reduce() if isinstance(pauli_sum, SummedOp): return pauli_sum return pauli_sum.to_pauli_op() # type: ignore
[ドキュメント] def equals(self, other: OperatorBase) -> bool: """Check if other is equal to self. Note: This is not a mathematical check for equality. If ``self`` and ``other`` implement the same operation but differ in the representation (e.g. different type of summands) ``equals`` will evaluate to ``False``. Args: other: The other operator to check for equality. Returns: True, if other and self are equal, otherwise False. Examples: >>> from qiskit.opflow import X, Z >>> 2 * X == X + X True >>> X + Z == Z + X True """ self_reduced, other_reduced = self.reduce(), other.reduce() if not isinstance(other_reduced, type(self_reduced)): return False # check if reduced op is still a SummedOp if not isinstance(self_reduced, SummedOp): return self_reduced == other_reduced self_reduced = cast(SummedOp, self_reduced) other_reduced = cast(SummedOp, other_reduced) if len(self_reduced.oplist) != len(other_reduced.oplist): return False # absorb coeffs into the operators if self_reduced.coeff != 1: self_reduced = SummedOp([op * self_reduced.coeff for op in self_reduced.oplist]) if other_reduced.coeff != 1: other_reduced = SummedOp([op * other_reduced.coeff for op in other_reduced.oplist]) # compare independent of order return all(any(i == j for j in other_reduced) for i in self_reduced)