DWave Tabu Sampler¶
A dimod sampler_ that uses the MST2 multistart tabu search algorithm.

class
TabuSampler
[source]¶ A tabusearch sampler.
Examples
This example solves a twovariable Ising model.
>>> from tabu import TabuSampler >>> samples = TabuSampler().sample_ising({'a': 0.5, 'b': 1.0}, {'ab': 1}) >>> list(samples.data()) # doctest: +SKIP [Sample(sample={'a': 1, 'b': 1}, energy=1.5, num_occurrences=1)] >>> samples.first.energy 1.5

sample
(bqm, initial_states=None, initial_states_generator='random', num_reads=None, tenure=None, timeout=20, scale_factor=1, **kwargs)[source]¶ Run Tabu search on a given binary quadratic model.
Parameters:  bqm (
BinaryQuadraticModel
) – The binary quadratic model (BQM) to be sampled.  initial_states (
SampleSet
, optional, default=None) – One or more samples, each defining an initial state for all the problem variables. Initial states are given one per read, but if fewer than num_reads initial states are defined, additional values are generated as specified by initial_states_generator.  initial_states_generator (str, 'none'/'tile'/'random', optional, default='random') –
Defines the expansion of initial_states if fewer than num_reads are specified:
 ”none”:
 If the number of initial states specified is smaller than num_reads, raises ValueError.
 ”tile”:
 Reuses the specified initial states if fewer than num_reads or truncates if greater.
 ”random”:
 Expands the specified initial states with randomly generated states if fewer than num_reads or truncates if greater.
 num_reads (int, optional, default=len(initial_states) or 1) – Number of reads. Each read is generated by one run of the tabu algorithm. If num_reads is not explicitly given, it is selected to match the number of initial states given. If initial states are not provided, only one read is performed.
 tenure (int, optional) – Tabu tenure, which is the length of the tabu list, or number of recently explored solutions kept in memory. Default is a quarter of the number of problem variables up to a maximum value of 20.
 timeout (int, optional) – Total running time in milliseconds.
 scale_factor (number, optional) – Scaling factor for linear and quadratic biases in the BQM. Internally, the BQM is
converted to a QUBO matrix, and elements are stored as long ints
using
internal_q = long int (q * scale_factor)
.  init_solution (
SampleSet
, optional) – Deprecated. Alias for initial_states.
Returns: A dimod
SampleSet
object.Return type: Examples
This example samples a simple twovariable Ising model.
>>> import dimod >>> bqm = dimod.BQM.from_ising({}, {'ab': 1})
>>> import tabu >>> sampler = tabu.TabuSampler()
>>> samples = sampler.sample(bqm) >>> samples.record[0].energy 1.0
 bqm (
