HigherOrder Composites¶
The dimod package includes several example higherorder composed samplers.
HigherOrderComposite¶

class
HigherOrderComposite
(child_sampler)[source]¶ Convert a binary quadratic model sampler to a binary polynomial sampler.
Energies of the returned samples do not include the penalties.
 Parameters
sampler (
dimod.Sampler
) – A dimod sampler
Example
This example uses
HigherOrderComposite
to instantiate a composed sampler that submits a simple Ising problem to a sampler. The composed sampler creates a binary quadratic model (BQM) from a higher order problem.>>> sampler = dimod.HigherOrderComposite(dimod.ExactSolver()) >>> h = {0: 0.5, 1: 0.3, 2: 0.8} >>> J = {(0, 1, 2): 1.7} >>> sampleset = sampler.sample_hising(h, J, discard_unsatisfied=True) >>> set(sampleset.first.sample.values()) == {1} True
Properties¶
The child sampler. 

A list containing the wrapped sampler. 

A dict where keys are the keyword parameters accepted by the sampler methods and values are lists of the properties relevant to each parameter. 

A dict containing any additional information about the sampler. 
Methods¶

Sample from the given binary polynomial. 

Sample from a higherorder Ising model. 

Sample from a higherorder unconstrained binary optimization problem. 
PolyFixedVariableComposite¶

class
PolyFixedVariableComposite
(child_sampler)[source]¶ Composite that fixes variables of a problem.
Fixes variables of a binary polynomial and modifies linear and klocal terms accordingly. Returned samples include the fixed variable.
 Parameters
sampler (
dimod.PolySampler
) – A dimod polynomial sampler.
Examples
This example uses
PolyFixedVariableComposite
to instantiate a composed sampler that submits a simple highorder Ising problem to a sampler. The composed sampler fixes a variable and modifies linear and klocal terms biases.>>> h = {1: 1.3, 2: 1.2, 3: 3.4, 4: 0.5} >>> J = {(1, 4): 0.6, (1, 2, 3): 0.2, (1, 2, 3, 4): 0.1} >>> poly = dimod.BinaryPolynomial.from_hising(h, J, offset=0) >>> sampler = dimod.PolyFixedVariableComposite(dimod.ExactPolySolver()) >>> sampleset = sampler.sample_poly(poly, fixed_variables={3: 1, 4: 1})
Properties¶
The child sampler. 

List of child samplers that that are used by this composite. 

A dict where keys are the keyword parameters accepted by the sampler methods and values are lists of the properties relevant to each parameter. 

A dict containing any additional information about the sampler. 
Methods¶
Sample from the provided binary quadratic model. 

Sample from a higherorder Ising model. 

Sample from a higherorder unconstrained binary optimization problem. 
PolyScaleComposite¶

class
PolyScaleComposite
(child)[source]¶ Composite to scale biases of a binary polynomial.
 Parameters
child (
PolySampler
) – A binary polynomial sampler.
Examples
>>> linear = {'a': 4.0, 'b': 4.0} >>> quadratic = {('a', 'b'): 3.2, ('a', 'b', 'c'): 1} >>> sampler = dimod.PolyScaleComposite(dimod.HigherOrderComposite(dimod.ExactSolver())) >>> response = sampler.sample_hising(linear, quadratic, scalar=0.5, ... ignored_terms=[('a','b')])
Properties¶
The child sampler. 

The child sampler in a list 

A dict where keys are the keyword parameters accepted by the sampler methods and values are lists of the properties relevant to each parameter. 

A dict containing any additional information about the sampler. 
Methods¶

Scale and sample from the given binary polynomial. 

Sample from a higherorder Ising model. 

Sample from a higherorder unconstrained binary optimization problem. 
PolyTruncateComposite¶

class
PolyTruncateComposite
(child_sampler, n, sorted_by='energy', aggregate=False)[source]¶ Composite that truncates returned samples.
Postprocessing is expensive and sometimes one might want to only treat the lowestenergy samples. This composite layer allows one to preselect the samples within a multicomposite pipeline.
 Parameters
child_sampler (
dimod.PolySampler
) – A dimod binary polynomial sampler.n (int) – Maximum number of rows in the returned sample set.
sorted_by (str/None, optional, default='energy') – Selects the record field used to sort the samples before truncating. Note that sample order is maintained in the underlying array.
aggregate (bool, optional, default=False) – If True, aggregate the samples before truncating.
Note
If aggregate is True,
SampleSet.record.num_occurrences
are accumulated but no other fields are.
Properties¶
The child sampler. 

List of child samplers that that are used by this composite. 

A dict where keys are the keyword parameters accepted by the sampler methods and values are lists of the properties relevant to each parameter. 

A dict containing any additional information about the sampler. 
Methods¶

Sample from the binary polynomial and truncate output. 

Sample from a higherorder Ising model. 

Sample from a higherorder unconstrained binary optimization problem. 