dimod.ConstrainedQuadraticModel.add_discrete_from_comparison

ConstrainedQuadraticModel.add_discrete_from_comparison(comp: dimod.sym.Comparison, label: Optional[Hashable] = None, copy: bool = True) Hashable[source]

Add a one-hot constraint from a comparison.

One-hot constraints can represent discrete variables (for example a color variable that has values {"red", "blue", "green"}) by requiring that only one of a set of two or more binary variables is assigned a value of 1.

These constraints support only BINARY variables and must be disjoint; that is, variables in such a constraint must not be used elsewhere in the model.

Constraints added by this method are guaranteed to be satisfied in solutions returned by the LeapHybridCQMSampler hybrid sampler.

Parameters
  • comp – Comparison object. The comparison must be a linear equality constraint with all of the linear biases on the left-hand side equal to one and the right hand side equal to one.

  • label – Label for the constraint. Must be unique. If no label is provided, one is generated using uuid.

  • copy – If True, the model used in the comparison is copied. You can set to False to improve performance, but subsequently mutating the model can cause issues.

Returns

Label of the added constraint.

Examples

>>> cqm = dimod.ConstrainedQuadraticModel()
>>> r, b, g = dimod.Binaries(["red", "blue", "green"])
>>> cqm.add_discrete_from_comparison(r + b + g == 1, label="One color")
'One color'