VirtualGraphComposite¶
Class¶
The D-Wave virtual graph tools simplify the process of minor-embedding by enabling you to more easily create, optimize, use, and reuse an embedding for a given working graph. When you submit an embedding and specify a chain strength using these tools, they automatically calibrate the qubits in a chain to compensate for the effects of biases that may be introduced as a result of strong couplings.
-
class
VirtualGraphComposite
(sampler, embedding, chain_strength=None, flux_biases=None, flux_bias_num_reads=1000, flux_bias_max_age=3600)[source]¶ Apply the VirtualGraph composite layer to the given solver.
Parameters: - sampler (
DWaveSampler
) – A dimoddimod.Sampler
. NormallyDWaveSampler
, or a derived composite sampler. Other samplers in general will not work or will not make sense with this composite layer. - embedding (dict[hashable, iterable]) – A mapping from a source graph to the given sampler’s graph (the target graph).
- chain_strength (float, optional, default=None) – The desired chain strength. If None, will use the maximum available from the processor.
- flux_biases (list/False/None, optional, default=None) – The per-qubit flux bias offsets. If given, should be a list of lists. Each sublist should be of length 2 and is the variable and the flux bias offset associated with the variable. If flux_biases evaluates False, then no flux bias is applied or calculated. If None if given, the flux biases are pulled from the database or calculated empirically.
- flux_bias_num_reads (int, optional, default=1000) – The number of samples to collect per flux bias value.
- flux_bias_max_age (int, optional, default=3600) – The maximum age (in seconds) allowed for a previously calculated flux bias offset.
- sampler (
Sampler Properties¶
VirtualGraphComposite.properties |
dict – Contains one key 'child_properties' which has a copy of the child sampler’s properties. |
VirtualGraphComposite.parameters |
The same parameters as are accepted by the child sampler with an additional parameter ‘apply_flux_bias_offsets’. |
Composite Properties¶
VirtualGraphComposite.children |
list – A list containig the wrapped sampler. |
VirtualGraphComposite.child |
The first child in children . |
Structure Properties¶
VirtualGraphComposite.nodelist |
list – The nodes available to the sampler. |
VirtualGraphComposite.edgelist |
list – The edges available to the sampler. |
VirtualGraphComposite.adjacency |
dict[variable, set] – The adjacency structure. |
VirtualGraphComposite.structure |
A namedtuple Structure(nodelist, edgelist, adjacency) |
Methods¶
VirtualGraphComposite.sample (bqm, **parameters) |
Samples from the given bqm using the instantiated sample method. |
VirtualGraphComposite.sample_ising (h, J[, …]) |
Sample from the given Ising model. |
VirtualGraphComposite.sample_qubo (Q, …) |
Samples from the given QUBO using the instantiated sample method. |