"""This module contains the ``RandomSamplerSolver`` class."""
from __future__ import annotations
from typing import Any, SupportsInt
from dwave.samplers import RandomSampler
from numpy.random import RandomState
from tno.quantum.optimization.qubo.components import QUBO, Solver
from tno.quantum.optimization.qubo.solvers._dwave._dimod_sample_set_result import (
DimodSampleSetResult,
)
from tno.quantum.optimization.qubo.solvers._dwave._utils import get_singleton
from tno.quantum.utils.validation import check_int, check_random_state
[docs]class RandomSamplerSolver(Solver[DimodSampleSetResult]):
"""D-Wave random sampler solver.
The :py:class:`RandomSamplerSolver` class samples random states from the QUBOs
solution space using the D-Wave :py:class:`~dwave.samplers.RandomSampler`.
Example:
>>> from tno.quantum.optimization.qubo.components import QUBO
>>> from tno.quantum.optimization.qubo.solvers import RandomSamplerSolver
>>>
>>> qubo = QUBO([[1, 2, 3], [4, -50, 6], [7, 8, 9]])
>>> solver = RandomSamplerSolver()
>>> result = solver.solve(qubo)
>>> result.best_bitvector # doctest: +ELLIPSIS
BitVector(...)
"""
[docs] def __init__(
self,
*,
random_state: int | RandomState | None = None,
num_reads: SupportsInt = 1,
**sample_kwargs: Any,
) -> None:
"""Init :py:class:`RandomSamplerSolver`.
Args:
random_state: Random state for reproducibility. Overrides the D-Waves
``'seed'`` argument. Default is ``None``.
num_reads: Maximum number of random samples to be drawn. Default is 1.
sample_kwargs: Additional keyword arguments that can be used for the
sampler. See the D-Wave documentation of
:py:meth:`~dwave.samplers.RandomSampler.sample` for possible additional
keyword definitions.
Raises:
ValueError: If `random_state` has invalid value, or if `num_reads` is less
than 1.
TypeError: If `num_reads` is not an integer.
"""
self.sampler = get_singleton(RandomSampler)
self.random_state = check_random_state(random_state, "random_state")
self.num_reads = check_int(num_reads, "num_reads", l_bound=1)
self.sample_kwargs = sample_kwargs
def _solve(self, qubo: QUBO) -> DimodSampleSetResult:
"""Solve QUBO using the D-Wave ``RandomSampler``."""
# Use seed from sample_kwargs, or generate one using random_state
seed = self.sample_kwargs.get("seed", self.random_state.randint(2**31))
kwargs = dict(self.sample_kwargs)
kwargs.pop("seed", None)
kwargs.pop("num_reads", None)
response = self.sampler.sample(
qubo.to_bqm(),
seed=seed,
num_reads=self.num_reads,
**kwargs,
)
return DimodSampleSetResult.from_result(qubo, response)