dwave.embedding.chain_breaks.majority_vote

majority_vote(samples, chains)

Unembed samples using the most common value for broken chains.

Parameters:

• samples (samples_like) – A collection of samples. samples_like is an extension of NumPy’s array-like. See dimod.as_samples().

• chains (list[array-like]) – List of chains, where each chain is an array-like collection of the variables in the same order as their representation in the given samples.

Returns:

A 2-tuple containing:

numpy.ndarray: Unembedded samples as an \(nS \times nC\) array of dtype int8, where \(nC\) is the number of chains and \(nS\) the number of samples. Broken chains are resolved by setting the sample value to that of most the chain’s elements or, for chains without a majority, an arbitrary value.

numpy.ndarray: Indices of the samples. Equivalent to np.arange(nS) because all samples are kept and none added.

Return type:

tuple

Examples

This example unembeds samples from a target graph that chains nodes 0 and 1 to represent one source node and nodes 2, 3, and 4 to represent another. Both samples have one broken chain, with different majority values.

>>> import numpy as np
>>> import dimod
...
>>> chains = [(0, 1), (2, 3, 4)]
>>> samples = np.array([[1, 1, 0, 0, 1], [1, 1, 1, 0, 1]], dtype=np.int8)
>>> unembedded, idx = dwave.embedding.majority_vote(samples, chains)
>>> print(unembedded)
[[1 0]
 [1 1]]
>>> print(idx)
[0 1]