# -*- coding: utf-8 -*-
# This code is part of Qiskit.
#
# (C) Copyright IBM 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.
"""A simulator instruction to capture output within a simulation. The types of snapshot
instructions available are determined by the simulator being used.
"""
import warnings
from typing import Optional
from ..channels import SnapshotChannel
from .instruction import Instruction
[docs]class Snapshot(Instruction):
"""An instruction targeted for simulators, to capture a moment in the simulation."""
def __init__(self, label: str, snapshot_type: str = 'statevector', name: Optional[str] = None):
"""Create new snapshot.
Args:
label: Snapshot label which is used to identify the snapshot in the output.
snapshot_type: Type of snapshot, e.g., “state” (take a snapshot of the quantum state).
The types of snapshots offered are defined by the simulator used.
name: Snapshot name which defaults to ``label``. This parameter is only for display
purposes and is not taken into account during comparison.
"""
self._label = label
self._type = snapshot_type
self._channel = SnapshotChannel()
if name is None:
name = self.label
super().__init__((label, snapshot_type), 0, (self.channel,), name=name)
@property
def label(self) -> str:
"""Label of snapshot."""
return self._label
@property
def type(self) -> str:
"""Type of snapshot."""
return self._type
@property
def channel(self) -> SnapshotChannel:
"""Return the :py:class:`~qiskit.pulse.channels.Channel` that this instruction is
scheduled on; trivially, a ``SnapshotChannel``.
"""
return self._channel
[docs] def __call__(self):
"""Deprecated."""
warnings.warn("Snapshot call method is deprecated.", DeprecationWarning)
return self