dimod.ConstrainedQuadraticModel.add_constraint_from_model

ConstrainedQuadraticModel.add_constraint_from_model(qm: Union[dimod.binary.binary_quadratic_model.BinaryQuadraticModel, dimod.quadratic.quadratic_model.QuadraticModel], sense: Union[dimod.sym.Sense, str], rhs: Union[float, numpy.floating, numpy.integer] = 0, label: Optional[Hashable] = None, copy: bool = True) → Hashable[source]

Add a constraint from a quadratic model.

Parameters

  • qm – Quadratic model or binary quadratic model.

  • sense – One of <=, >=, ==.

  • rhs – Right hand side of the constraint.

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

  • copy – If True, model qm is copied. This can be set to False to improve performance, but subsequently mutating qm can cause issues.

Returns

Label of the added constraint.

Examples

This example adds a constraint from the single-variable binary quadratic model x.

>>> from dimod import ConstrainedQuadraticModel, Binary
>>> cqm = ConstrainedQuadraticModel()
>>> x = Binary('x')
>>> cqm.add_constraint_from_model(x, '>=', 0, 'Min x')
'Min x'
>>> print(cqm.constraints["Min x"].to_polystring())
x >= 0

Adding a constraint without copying the model requires caution:

>>> cqm.add_constraint_from_model(x, "<=", 3, "Risky constraint", copy=False)
'Risky constraint'
>>> x *= 2
>>> print(cqm.constraints["Risky constraint"].to_polystring())
2*x <= 3