Quellcode für qiskit.circuit.parameter

# This code is part of Qiskit.
#
# (C) Copyright IBM 2017, 2019.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.
"""
Parameter Class for variable parameters.
"""

from uuid import uuid4

from qiskit.circuit.exceptions import CircuitError
from qiskit.utils import optionals as _optionals

from .parameterexpression import ParameterExpression


[Doku]class Parameter(ParameterExpression): """Parameter Class for variable parameters. A parameter is a variable value that is not required to be fixed at circuit definition. Examples: Construct a variable-rotation X gate using circuit parameters. .. plot:: :include-source: from qiskit.circuit import QuantumCircuit, Parameter # create the parameter phi = Parameter('phi') qc = QuantumCircuit(1) # parameterize the rotation qc.rx(phi, 0) qc.draw('mpl') # bind the parameters after circuit to create a bound circuit bc = qc.bind_parameters({phi: 3.14}) bc.measure_all() bc.draw('mpl') """ __slots__ = ("_name", "_uuid", "_hash") def __new__(cls, name, uuid=None): # pylint: disable=unused-argument # Parameter relies on self._uuid being set prior to other attributes # (e.g. symbol_map) which may depend on self._uuid for Parameter's hash # or __eq__ functions. obj = object.__new__(cls) if uuid is None: obj._uuid = uuid4() else: obj._uuid = uuid obj._hash = hash(obj._uuid) return obj def __getnewargs__(self): # Unpickling won't in general call __init__ but will always call # __new__. Specify arguments to be passed to __new__ when unpickling. return (self.name, self._uuid) def __init__(self, name: str): """Create a new named :class:`Parameter`. Args: name: name of the ``Parameter``, used for visual representation. This can be any unicode string, e.g. "ϕ". """ self._name = name if not _optionals.HAS_SYMENGINE: from sympy import Symbol symbol = Symbol(name) else: import symengine symbol = symengine.Symbol(name) super().__init__(symbol_map={self: symbol}, expr=symbol)
[Doku] def subs(self, parameter_map: dict, allow_unknown_parameters: bool = False): """Substitute self with the corresponding parameter in ``parameter_map``.""" if self in parameter_map: return parameter_map[self] if allow_unknown_parameters: return self raise CircuitError( "Cannot bind Parameters ({}) not present in " "expression.".format([str(p) for p in parameter_map]) )
@property def name(self): """Returns the name of the :class:`Parameter`.""" return self._name def __str__(self): return self.name def __copy__(self): return self def __deepcopy__(self, memo=None): return self def __repr__(self): return f"{self.__class__.__name__}({self.name})" def __eq__(self, other): if isinstance(other, Parameter): return self._uuid == other._uuid elif isinstance(other, ParameterExpression): return super().__eq__(other) else: return False def __hash__(self): return self._hash def __getstate__(self): return {"name": self._name} def __setstate__(self, state): self._name = state["name"] if not _optionals.HAS_SYMENGINE: from sympy import Symbol symbol = Symbol(self._name) else: import symengine symbol = symengine.Symbol(self._name) super().__init__(symbol_map={self: symbol}, expr=symbol)