bug in core/base/sos.py

[DLWoodruff]

taken from core/base/sos.py docstring and modified slightly

import pyomo.environ as pyo
model = pyo.ConcreteModel()
model.A = pyo.Set(initialize = range(2))
model.B = pyo.Set(model.A, initialize={1: "hello", 2: "goodbye"})
model.X = pyo.Var(model.B)
model.C1 = pyo.SOSConstraint(model.A, var=model.X, set=model.B, sos=1)

According to the docstring in core/base/sos.py:

This constraint actually creates one SOS-1 constraint for each
element of model.A (e.g., if |A| == N, there are N constraints).
In each constraint, model.X is indexed by the elements of
model.B[a], where 'a' is the current index of model.A.

But, this example cannot run at all because a Var cannot be indexed by an indexed Set.

#So maybe this is sort of what was meant :
import pyomo.environ as pyo
model = pyo.ConcreteModel()
model.A = pyo.Set(initialize = range(2))
model.B = pyo.Set(initialize=["hello", "goodbye"])
model.C = model.A * model.B
model.X = pyo.Var(model.C)
model.C1 = pyo.SOSConstraint(model.A, var=model.X, set=model.C, sos=1)

This example results in:

ValueError: Unexpected keyword options found while constructing 'IndexedSOSConstraint':
    set

[tkorvola]

More bugs in the SOSConstraint docstring:

• The keyword for SET is index; set is not recognized.
• N does not default to 1 but must be specified.
• There is an alternative way to call the constructor, which is not documented at all: instead of var, index and weights one specifies a rule, which is called in the usual manner.

[mrmundt]

This theoretically was addressed in the linked PR, so closing this issue. Please open a new one if there are still concerns.