openjij.sampler

openjij.sampler#

Submodules#

Classes#

`CSQASampler`	Sampler with continuous-time simulated quantum annealing (CSQA) using
`Response`	Samples and any other data returned by dimod samplers.
`SASampler`	Sampler with Simulated Annealing (SA).
`SQASampler`	Sampler with Simulated Quantum Annealing (SQA).

Functions#

measure_time(func)

Decorator for measuring calculation time.

Package Contents#

class openjij.sampler.CSQASampler(beta=5.0, gamma=1.0, num_sweeps=1000, schedule=None, num_reads=1)[source]#

Bases: openjij.sampler.sqa_sampler.SQASampler

Inheritance diagram of openjij.sampler.CSQASampler

Sampler with continuous-time simulated quantum annealing (CSQA) using

Hamiltonian.

H(s) = s H_p + \Gamma (1-s)\sum_i \sigma_i^x

where $H_p$ is the problem Hamiltonian we want to solve.

Parameters:

beta (float) – Inverse temperature.
gamma (float) – Amplitude of quantum fluctuation.
schedule (list) – schedule list
step_num (int) – Number of Monte Carlo step.
schedule_info (dict) – Information about a annealing schedule.
num_reads (int) – Number of iterations.
num_sweeps (int) – number of sweeps
schedule_info – Information about a annealing schedule.

remove_unknown_kwargs(**kwargs) → Dict[str, Any]#

Remove with warnings any keyword arguments not accepted by the sampler.

Parameters:: **kwargs – Keyword arguments to be validated.
Return type:: Dict[str, Any]

Returns: Updated kwargs dict.

Examples

>>> import warnings
>>> sampler = dimod.RandomSampler()
>>> with warnings.catch_warnings():
...     warnings.filterwarnings('ignore')
...     try:
...         sampler.remove_unknown_kwargs(num_reads=10, non_param=3)
...     except dimod.exceptions.SamplerUnknownArgWarning:
...        pass
{'num_reads': 10}

Sampling from the Ising model.

Parameters:

bqm (openjij.BinaryQuadraticModel)
beta (float, optional) – inverse tempareture.
gamma (float, optional) – strangth of transverse field. Defaults to None.
num_sweeps (int, optional) – number of sweeps. Defaults to None.
schedule (list[list[float, int]], optional) – List of annealing parameter. Defaults to None.
trotter (int) – Trotter number.
num_reads (int, optional) – number of sampling. Defaults to 1.
initial_state (list[int], optional) – Initial state. Defaults to None.
updater (str, optional) – update method. Defaults to ‘single spin flip’.
sparse (bool) – use sparse matrix or not.
reinitialize_state (bool, optional) – Re-initilization at each sampling. Defaults to True.
seed (int, optional) – Sampling seed. Defaults to None.

Raises:

ValueError –

Returns:

results

Return type:

openjij.sampler.response.Response

Examples

for Ising case:

>>> h = {0: -1, 1: -1, 2: 1, 3: 1}
>>> J = {(0, 1): -1, (3, 4): -1}
>>> sampler = openjij.SQASampler()
>>> res = sampler.sample_ising(h, J)

for QUBO case:

>>> Q = {(0, 0): -1, (1, 1): -1, (2, 2): 1, (3, 3): 1, (4, 4): 1, (0, 1): -1, (3, 4): 1}
>>> sampler = openjij.SQASampler()
>>> res = sampler.sample_qubo(Q)

sample_ising(h, J, beta: float = 5.0, gamma: float = 1.0, num_sweeps: int = 1000, schedule=None, num_reads: int = 1, initial_state=None, updater=None, reinitialize_state=True, seed=None)[source]#

Sampling from the Ising model.

Parameters:

h (dict) – linear biases
J (dict) – quadratic biases
beta (float, optional) – inverse temperature
gamma (float, optional) – strength of transverse field
num_sweeps (int, optional) – number of sampling.
schedule (list, optional) – schedule list
num_reads (int, optional) – number of iterations
initial_state (optional) – initial state of spins
updater (str, optional) – updater algorithm
reinitialize_state (bool, optional) – Re-initilization at each sampling. Defaults to True.
seed (int, optional) – Sampling seed.

Returns:

results

Return type:

openjij.sampler.response.Response

Examples

for Ising case:

>>> h = {0: -1, 1: -1, 2: 1, 3: 1}
>>> J = {(0, 1): -1, (3, 4): -1}
>>> sampler = openjij.CSQASampler()
>>> res = sampler.sample_ising(h, J)

for QUBO case:

>>> Q = {(0, 0): -1, (1, 1): -1, (2, 2): 1, (3, 3): 1, (4, 4): 1, (0, 1): -1, (3, 4): 1}
>>> sampler = openjijj.CSQASampler()
>>> res = sampler.sample_qubo(Q)

sample_qubo(Q, **parameters)#

Sample from a QUBO model using the implemented sample method.

Parameters:: Q (dict or numpy.ndarray) – Coefficients of a quadratic unconstrained binary optimization
Returns:: results
Return type:: openjij.sampler.response.Response

property parameters#
Parameters as a dict, where keys are keyword parameters accepted by the
sampler methods and values are lists of the properties relevent to each
parameter.

properties#

class openjij.sampler.Response(record, variables, info, vartype)[source]#

Bases: dimod.SampleSet

Inheritance diagram of openjij.sampler.Response

Samples and any other data returned by dimod samplers.

Parameters:

record (:obj:`numpy.recarray`) – A NumPy record array. Must have ‘sample’, ‘energy’ and ‘num_occurrences’ as fields. The ‘sample’ field should be a 2D NumPy array where each row is a sample and each column represents the value of a variable.
variables (iterable) – An iterable of variable labels, corresponding to columns in record.samples.
info (dict) – Information about the SampleSet as a whole, formatted as a dict.
vartype (:class:.Vartype`/str/set`) –
Variable type for the SampleSet. Accepted input values:
- Vartype.SPIN, 'SPIN', {-1, 1}
- Vartype.BINARY, 'BINARY', {0, 1}
- ExtendedVartype.DISCRETE, 'DISCRETE'

Examples

This example creates a SampleSet out of a samples_like object (a NumPy array).

>>> import numpy as np
...
>>> sampleset =  dimod.SampleSet.from_samples(np.ones(5, dtype='int8'),
...                                           'BINARY', 0)
>>> sampleset.variables
Variables([0, 1, 2, 3, 4])

aggregate()#

Create a new SampleSet with repeated samples aggregated.

Returns:: SampleSet

Note

SampleSet.record.num_occurrences are accumulated but no other fields are.

Examples

This examples aggregates a sample set with two identical samples out of three.

>>> sampleset = dimod.SampleSet.from_samples([[0, 0, 1], [0, 0, 1],
...                                           [1, 1, 1]],
...                                           dimod.BINARY,
...                                           [0, 0, 1])
>>> print(sampleset)
   0  1  2 energy num_oc.
0  0  0  1      0       1
1  0  0  1      0       1
2  1  1  1      1       1
['BINARY', 3 rows, 3 samples, 3 variables]
>>> print(sampleset.aggregate())
   0  1  2 energy num_oc.
0  0  0  1      0       2
1  1  1  1      1       1
['BINARY', 2 rows, 3 samples, 3 variables]

append_variables(samples_like, sort_labels=True)#: Deprecated in favor of dimod.append_variables.

change_vartype(vartype, energy_offset=0.0, inplace=True)#

Return the SampleSet with the given vartype.

Parameters:

vartype (:class:.Vartype`/str/set`) –
Variable type to use for the new SampleSet. Accepted input values:
- Vartype.SPIN, 'SPIN', {-1, 1}
- Vartype.BINARY, 'BINARY', {0, 1}
energy_offset (number, optional, defaul=0.0) – Constant value applied to the ‘energy’ field of SampleSet.record.
inplace (bool, optional, default=True) – If True, the instantiated SampleSet is updated; otherwise, a new SampleSet is returned.

Returns:

SampleSet with changed vartype. If inplace is True, returns itself.

Return type:

SampleSet

Notes

This function is non-blocking unless inplace==True, in which case the sample set is resolved.

Examples

This example creates a binary copy of a spin-valued SampleSet.

>>> sampleset = dimod.ExactSolver().sample_ising({'a': -0.5, 'b': 1.0}, {('a', 'b'): -1})
>>> sampleset_binary = sampleset.change_vartype(dimod.BINARY, energy_offset=1.0, inplace=False)
>>> sampleset_binary.vartype is dimod.BINARY
True
>>> sampleset_binary.first.sample
{'a': 0, 'b': 0}

copy()#: Create a shallow copy.

data(fields=None, sorted_by='energy', name='Sample', reverse=False, sample_dict_cast=True, index=False)#

Iterate over the data in the SampleSet.

Parameters:

fields (list, optional, default=None) – If specified, only these fields are included in the yielded tuples. The special field name ‘sample’ can be used to view the samples.
sorted_by (str/None, optional, default='energy') – Selects the record field used to sort the samples. If None, the samples are yielded in record order.
name (str/None, optional, default='Sample') – Name of the yielded namedtuples or None to yield regular tuples.
reverse (bool, optional, default=False) – If True, yield in reverse order.
sample_dict_cast (bool, optional, default=True) – Samples are returned as dicts rather than SampleView, which requires heavy memory usage. Set to False to reduce load on memory.
index (bool, optional, default=False) – If True, datum.idx gives the corresponding index of the SampleSet.record.

Yields:

namedtuple/tuple – The data in the SampleSet, in the order specified by the input fields.

Examples

>>> sampleset = dimod.ExactSolver().sample_ising({'a': -0.5, 'b': 1.0}, {('a', 'b'): -1})
>>> for datum in sampleset.data(fields=['sample', 'energy']):   
...     print(datum)
Sample(sample={'a': -1, 'b': -1}, energy=-1.5)
Sample(sample={'a': 1, 'b': -1}, energy=-0.5)
Sample(sample={'a': 1, 'b': 1}, energy=-0.5)
Sample(sample={'a': -1, 'b': 1}, energy=2.5)
>>> for energy, in sampleset.data(fields=['energy'], sorted_by='energy'):
...     print(energy)
...
-1.5
-0.5
-0.5
2.5
>>> print(next(sampleset.data(fields=['energy'], name='ExactSolverSample')))
ExactSolverSample(energy=-1.5)

done()#

Return True if a pending computation is done.

Used when a SampleSet is constructed with SampleSet.from_future().

Examples

This example uses a Future object directly. Typically a Executor sets the result of the future (see documentation for concurrent.futures).

>>> from concurrent.futures import Future
...
>>> future = Future()
>>> sampleset = dimod.SampleSet.from_future(future)
>>> future.done()
False
>>> future.set_result(dimod.ExactSolver().sample_ising({0: -1}, {}))
>>> future.done()
True
>>> sampleset.first.energy
-1.0

filter(pred: Callable[[Any], bool]) → SampleSet#

Return a new sampleset with rows filtered by the given predicate.

Parameters:: pred (Callable[[Any], bool]) – A function that accepts a named tuple as returned by data() and returns a bool.
Returns:: A new sample set with only the data rows for which pred returns True.
Return type:: SampleSet

Examples

>>> sampleset = dimod.SampleSet.from_samples(
...     [{'a': 1, 'b': 0}, {'a': 0, 'b': 1}],
...     vartype=dimod.BINARY,
...     energy=[0, 1],
...     is_feasible=[True, False]
...     )
>>> feasible_sampleset = sampleset.filter(lambda d: d.is_feasible)
>>> print(feasible_sampleset)
   a  b energy num_oc. is_fea.
0  1  0      0       1    True
['BINARY', 1 rows, 1 samples, 2 variables]

classmethod from_future(future, result_hook=None)#

Construct a SampleSet referencing the result of a future computation.

Parameters:

future (object) – Object that contains or will contain the information needed to construct a SampleSet. If future has a done() method, this determines the value returned by SampleSet.done().
result_hook (callable, optional) –
A function that is called to resolve the future. Must accept the future and return a SampleSet. If not provided, set to
```
def result_hook(future):
    return future.result()
```

Returns:

SampleSet

Notes

The future is resolved on the first read of any of the SampleSet properties.

Examples

Run a dimod sampler on a single thread and load the returned future into SampleSet.

>>> from concurrent.futures import ThreadPoolExecutor
...
>>> bqm = dimod.BinaryQuadraticModel.from_ising({}, {('a', 'b'): -1})
>>> with ThreadPoolExecutor(max_workers=1) as executor:
...     future = executor.submit(dimod.ExactSolver().sample, bqm)
...     sampleset = dimod.SampleSet.from_future(future)
>>> sampleset.first.energy    

classmethod from_samples(samples_like, vartype, energy, info=None, num_occurrences=None, aggregate_samples=False, sort_labels=True, **vectors)#

Build a SampleSet from raw samples.

Parameters:

samples_like – A collection of raw samples. ‘samples_like’ is an extension of NumPy’s array_like. See as_samples().
vartype (:class:.Vartype`/str/set`) –
Variable type for the SampleSet. Accepted input values:
- Vartype.SPIN, 'SPIN', {-1, 1}
- Vartype.BINARY, 'BINARY', {0, 1}
- ExtendedVartype.DISCRETE, 'DISCRETE'
energy (array_like) – Vector of energies.
info (dict, optional) – Information about the SampleSet as a whole formatted as a dict.
num_occurrences (array_like, optional) – Number of occurrences for each sample. If not provided, defaults to a vector of 1s.
aggregate_samples (bool, optional, default=False) – If True, all samples in returned SampleSet are unique, with num_occurrences accounting for any duplicate samples in samples_like.
sort_labels (bool, optional, default=True) – Return SampleSet.variables in sorted order. For mixed (unsortable) types, the given order is maintained.
**vectors (array_like) – Other per-sample data.

Returns:

SampleSet

Examples

This example creates a SampleSet out of a samples_like object (a dict).

>>> import numpy as np
...
>>> sampleset = dimod.SampleSet.from_samples(
...   dimod.as_samples({'a': 0, 'b': 1, 'c': 0}), 'BINARY', 0)
>>> sampleset.variables
Variables(['a', 'b', 'c'])

classmethod from_samples_bqm(samples_like, bqm, **kwargs)#

Build a sample set from raw samples and a binary quadratic model.

The binary quadratic model is used to calculate energies and set the vartype.

Parameters:

samples_like – A collection of raw samples. ‘samples_like’ is an extension of NumPy’s array_like. See as_samples().
bqm (:obj:.BinaryQuadraticModel``) – A binary quadratic model.
info (dict, optional) – Information about the SampleSet as a whole formatted as a dict.
num_occurrences (array_like, optional) – Number of occurrences for each sample. If not provided, defaults to a vector of 1s.
aggregate_samples (bool, optional, default=False) – If True, all samples in returned SampleSet are unique, with num_occurrences accounting for any duplicate samples in samples_like.
sort_labels (bool, optional, default=True) – Return SampleSet.variables in sorted order. For mixed (unsortable) types, the given order is maintained.
**vectors (array_like) – Other per-sample data.

Returns:

SampleSet

Examples

>>> bqm = dimod.BinaryQuadraticModel.from_ising({}, {('a', 'b'): -1})
>>> sampleset = dimod.SampleSet.from_samples_bqm({'a': -1, 'b': 1}, bqm)

classmethod from_samples_cqm(samples_like, cqm, rtol=1e-06, atol=1e-08, **kwargs)#

Build a sample set from raw samples and a constrained quadratic model.

The constrained quadratic model is used to calculate energies and feasibility.

Parameters:

samples_like – A collection of raw samples. ‘samples_like’ is an extension of NumPy’s array_like. See as_samples().
cqm (:obj:.ConstrainedQuadraticModel``) – A constrained quadratic model.
rtol (float, optional, default=1e-6) – Relative tolerance for constraint violation. See ConstrainedQuadraticModel.check_feasible() for more information.
atol (float, optional, default=1e-8) – Absolute tolerance for constraint violations. See ConstrainedQuadraticModel.check_feasible() for more information.
info (dict, optional) – Information about the SampleSet as a whole formatted as a dict.
num_occurrences (array_like, optional) – Number of occurrences for each sample. If not provided, defaults to a vector of 1s.
aggregate_samples (bool, optional, default=False) – If True, all samples in returned SampleSet are unique, with num_occurrences accounting for any duplicate samples in samples_like.
sort_labels (bool, optional, default=True) – Return SampleSet.variables in sorted order. For mixed (unsortable) types, the given order is maintained.
**vectors (array_like) – Other per-sample data.

Returns:

SampleSet

Examples

>>> cqm = dimod.ConstrainedQuadraticModel()
>>> x, y, z = dimod.Binaries(['x', 'y', 'z'])
>>> cqm.set_objective(x*y + 2*y*z)
>>> label = cqm.add_constraint(x*y == 1, label='constraint_1')
>>> sampleset = dimod.SampleSet.from_samples_cqm({'x': 0, 'y': 1, 'z': 1}, cqm)

classmethod from_serializable(obj)#

Deserialize a SampleSet.

Parameters:: obj (dict) – A SampleSet serialized by to_serializable().
Returns:: SampleSet

Examples

This example encodes and decodes using JSON.

>>> import json
...
>>> samples = dimod.SampleSet.from_samples([-1, 1, -1], dimod.SPIN, energy=-.5)
>>> s = json.dumps(samples.to_serializable())
>>> new_samples = dimod.SampleSet.from_serializable(json.loads(s))

See also

from_serializable()

truncate(n, sorted_by='energy')#

Create a new sample set with up to n rows.

Parameters:

n (int) – Maximum number of rows in the returned sample set. Does not return any rows above this limit in the original sample set.
sorted_by (str/None, optional, default='energy') – Selects the record field used to sort the samples before truncating. Note that this sort order is maintained in the returned sample set.

Returns:

SampleSet

Examples

>>> import numpy as np
...
>>> sampleset = dimod.SampleSet.from_samples(np.ones((5, 5)), dimod.SPIN, energy=5)
>>> print(sampleset)
   0  1  2  3  4 energy num_oc.
0 +1 +1 +1 +1 +1      5       1
1 +1 +1 +1 +1 +1      5       1
2 +1 +1 +1 +1 +1      5       1
3 +1 +1 +1 +1 +1      5       1
4 +1 +1 +1 +1 +1      5       1
['SPIN', 5 rows, 5 samples, 5 variables]
>>> print(sampleset.truncate(2))
   0  1  2  3  4 energy num_oc.
0 +1 +1 +1 +1 +1      5       1
1 +1 +1 +1 +1 +1      5       1
['SPIN', 2 rows, 2 samples, 5 variables]

See:: SampleSet.slice()

property data_vectors#

The per-sample data in a vector.

Returns:: A dict where the keys are the fields in the record and the values are the corresponding arrays.
Return type:: dict

Examples

>>> sampleset = dimod.SampleSet.from_samples([[-1, 1], [1, 1]], dimod.SPIN,
                                             energy=[-1, 1])
>>> sampleset.data_vectors['energy']
array([-1,  1])

Note that this is equivalent to, and less performant than:

>>> sampleset = dimod.SampleSet.from_samples([[-1, 1], [1, 1]], dimod.SPIN,
                                             energy=[-1, 1])
>>> sampleset.record['energy']
array([-1,  1])

property energies#

property first#

Sample with the lowest-energy.

Raises:: ValueError – If empty.

Example

>>> sampleset = dimod.ExactSolver().sample_ising({'a': 1}, {('a', 'b'): 1})
>>> sampleset.first
Sample(sample={'a': -1, 'b': 1}, energy=-2.0, num_occurrences=1)

property indices#

property info#

Dict of information about the :class:`SampleSet` as a whole.

Examples

This example shows the type of information that might be returned by a dimod sampler by submitting a BQM that sets a value on a D-Wave system’s first listed coupler.

>>> from dwave.system import DWaveSampler    
>>> sampler = DWaveSampler()    
>>> bqm = dimod.BQM({}, {sampler.edgelist[0]: -1}, 0, dimod.SPIN)   
>>> sampler.sample(bqm).info   
{'timing': {'qpu_sampling_time': 315,
 'qpu_anneal_time_per_sample': 20,
 'qpu_readout_time_per_sample': 274,
 # Snipped above response for brevity

property min_samples#

property record#

:obj:`numpy.recarray` containing the samples, energies, number of occurences, and other sample data.

Examples

>>> sampler = dimod.ExactSolver()
>>> sampleset = sampler.sample_ising({'a': -0.5, 'b': 1.0}, {('a', 'b'): -1.0})
>>> sampleset.record.sample     
array([[-1, -1],
       [ 1, -1],
       [ 1,  1],
       [-1,  1]], dtype=int8)
>>> len(sampleset.record.energy)
4

property states#

property variables#
:class:`~.variables.Variables` of variable labels.: Corresponds to columns of the sample field of SampleSet.record.

property vartype#
:class:`.Vartype` of the samples.

class openjij.sampler.SASampler[source]#

Bases: openjij.sampler.sampler.BaseSampler

Inheritance diagram of openjij.sampler.SASampler

Sampler with Simulated Annealing (SA).

Parameters:

beta_min (float) – Minmum beta (inverse temperature). You can overwrite in methods .sample_*.
beta_max (float) – Maximum beta (inverse temperature). You can overwrite in methods .sample_*.
num_reads (int) – number of sampling (algorithm) runs. defaults None. You can overwrite in methods .sample_*.
num_sweeps (int) – number of MonteCarlo steps during SA. defaults None. You can overwrite in methods .sample_*.
schedule_info (dict) – Information about an annealing schedule.

Raises:

ValueError – If schedules or variables violate as below.
- not list or numpy.array. –
- not list of tuple (beta – float, step_length : int).
- beta is less than zero. –

remove_unknown_kwargs(**kwargs) → Dict[str, Any]#

Remove with warnings any keyword arguments not accepted by the sampler.

Parameters:: **kwargs – Keyword arguments to be validated.
Return type:: Dict[str, Any]

Returns: Updated kwargs dict.

Examples

>>> import warnings
>>> sampler = dimod.RandomSampler()
>>> with warnings.catch_warnings():
...     warnings.filterwarnings('ignore')
...     try:
...         sampler.remove_unknown_kwargs(num_reads=10, non_param=3)
...     except dimod.exceptions.SamplerUnknownArgWarning:
...        pass
{'num_reads': 10}

Sample Ising model.

Parameters:

bqm (openjij.model.model.BinaryQuadraticModel)
beta_min (float) – minimal value of inverse temperature
beta_max (float) – maximum value of inverse temperature
num_sweeps (int) – number of sweeps
num_reads (int) – number of reads
schedule (list) – list of inverse temperature
initial_state (dict) – initial state
updater (str) – updater algorithm
sparse (bool) – use sparse matrix or not.
reinitialize_state (bool) – if true reinitialize state for each run
seed (int) – seed for Monte Carlo algorithm

Returns:

results

Return type:

openjij.sampler.response.Response

Examples

for Ising case:

>>> h = {0: -1, 1: -1, 2: 1, 3: 1}
>>> J = {(0, 1): -1, (3, 4): -1}
>>> sampler = openj.SASampler()
>>> res = sampler.sample_ising(h, J)

for QUBO case:

>>> Q = {(0, 0): -1, (1, 1): -1, (2, 2): 1, (3, 3): 1, (4, 4): 1, (0, 1): -1, (3, 4): 1}
>>> sampler = openj.SASampler()
>>> res = sampler.sample_qubo(Q)

sample_hubo(J: dict[tuple, float], vartype: str | None = None, num_sweeps: int = 1000, num_reads: int = 1, num_threads: int = 1, beta_min: float | None = None, beta_max: float | None = None, updater: str = 'METROPOLIS', random_number_engine: str = 'XORSHIFT', seed: int | None = None, temperature_schedule: str = 'GEOMETRIC')[source]#

Sampling from higher order unconstrainted binary optimization.

Parameters:

J (dict) – Interactions.
vartype (str) – “SPIN” or “BINARY”.
num_sweeps (int, optional) – The number of sweeps. Defaults to 1000.
num_reads (int, optional) – The number of reads. Defaults to 1.
num_threads (int, optional) – The number of threads. Parallelized for each sampling with num_reads > 1. Defaults to 1.
beta_min (float, optional) – Minimum beta (initial inverse temperature). Defaults to None.
beta_max (float, optional) – Maximum beta (final inverse temperature). Defaults to None.
updater (str, optional) – Updater. One can choose “METROPOLIS”, “HEAT_BATH”, or “k-local”. Defaults to “METROPOLIS”.
random_number_engine (str, optional) – Random number engine. One can choose “XORSHIFT”, “MT”, or “MT_64”. Defaults to “XORSHIFT”.
seed (int, optional) – seed for Monte Carlo algorithm. Defaults to None.
temperature_schedule (str, optional) – Temperature schedule. One can choose “LINEAR”, “GEOMETRIC”. Defaults to “GEOMETRIC”.

Returns:

results

Return type:

openjij.sampler.response.Response

Examples::

for Ising case::

>>> sampler = openjij.SASampler()
>>> J = {(0,): -1, (0, 1): -1, (0, 1, 2): 1}
>>> response = sampler.sample_hubo(J, "SPIN")

for Binary case::

>>> sampler = ooenjij.SASampler()
>>> J = {(0,): -1, (0, 1): -1, (0, 1, 2): 1}
>>> response = sampler.sample_hubo(J, "BINARY")

sample_ising(h, J, **parameters)#

Sample from an Ising model using the implemented sample method.

Parameters:

h (dict) – Linear biases
J (dict) – Quadratic biases

Returns:

results

Return type:

openjij.sampler.response.Response

sample_qubo(Q, **parameters)#

Sample from a QUBO model using the implemented sample method.

Parameters:: Q (dict or numpy.ndarray) – Coefficients of a quadratic unconstrained binary optimization
Returns:: results
Return type:: openjij.sampler.response.Response

property parameters#
Parameters as a dict, where keys are keyword parameters accepted by the
sampler methods and values are lists of the properties relevent to each
parameter.

properties#

class openjij.sampler.SQASampler[source]#

Bases: openjij.sampler.sampler.BaseSampler

Inheritance diagram of openjij.sampler.SQASampler

Sampler with Simulated Quantum Annealing (SQA).

Inherits from openjij.sampler.sampler.BaseSampler. Hamiltonian

H(s) = s H_p + \Gamma (1-s)\sum_i \sigma_i^x

where $H_p$ is the problem Hamiltonian we want to solve.

Parameters:

beta (float) – Inverse temperature.
gamma (float) – Amplitude of quantum fluctuation.
trotter (int) – Trotter number.
num_sweeps (int) – number of sweeps
schedule (list) – schedule list
num_reads (int) – Number of iterations.
schedule_info (dict) – Information about a annealing schedule.

Raises:

ValueError – If the schedule violates as below.
- not list or numpy.array. –
- schedule range is '0 <= s <= 1'. –

remove_unknown_kwargs(**kwargs) → Dict[str, Any]#

Remove with warnings any keyword arguments not accepted by the sampler.

Parameters:: **kwargs – Keyword arguments to be validated.
Return type:: Dict[str, Any]

Returns: Updated kwargs dict.

Examples

>>> import warnings
>>> sampler = dimod.RandomSampler()
>>> with warnings.catch_warnings():
...     warnings.filterwarnings('ignore')
...     try:
...         sampler.remove_unknown_kwargs(num_reads=10, non_param=3)
...     except dimod.exceptions.SamplerUnknownArgWarning:
...        pass
{'num_reads': 10}

Sampling from the Ising model.

Parameters:

bqm (openjij.BinaryQuadraticModel)
beta (float, optional) – inverse tempareture.
gamma (float, optional) – strangth of transverse field. Defaults to None.
num_sweeps (int, optional) – number of sweeps. Defaults to None.
schedule (list[list[float, int]], optional) – List of annealing parameter. Defaults to None.
trotter (int) – Trotter number.
num_reads (int, optional) – number of sampling. Defaults to 1.
initial_state (list[int], optional) – Initial state. Defaults to None.
updater (str, optional) – update method. Defaults to ‘single spin flip’.
sparse (bool) – use sparse matrix or not.
reinitialize_state (bool, optional) – Re-initilization at each sampling. Defaults to True.
seed (int, optional) – Sampling seed. Defaults to None.

Raises:

ValueError –

Returns:

results

Return type:

openjij.sampler.response.Response

Examples

for Ising case:

>>> h = {0: -1, 1: -1, 2: 1, 3: 1}
>>> J = {(0, 1): -1, (3, 4): -1}
>>> sampler = openjij.SQASampler()
>>> res = sampler.sample_ising(h, J)

for QUBO case:

>>> Q = {(0, 0): -1, (1, 1): -1, (2, 2): 1, (3, 3): 1, (4, 4): 1, (0, 1): -1, (3, 4): 1}
>>> sampler = openjij.SQASampler()
>>> res = sampler.sample_qubo(Q)

sample_ising(h, J, **parameters)#

Sample from an Ising model using the implemented sample method.

Parameters:

h (dict) – Linear biases
J (dict) – Quadratic biases

Returns:

results

Return type:

openjij.sampler.response.Response

sample_qubo(Q, **parameters)#

Sample from a QUBO model using the implemented sample method.

Parameters:: Q (dict or numpy.ndarray) – Coefficients of a quadratic unconstrained binary optimization
Returns:: results
Return type:: openjij.sampler.response.Response

property parameters#
Parameters as a dict, where keys are keyword parameters accepted by the
sampler methods and values are lists of the properties relevent to each
parameter.

properties#

openjij.sampler.measure_time(func)[source]#

Decorator for measuring calculation time.

Parameters:: func – decorator function