Search code examples
pythonindexingpyomo

Pyomo Cannot index a component with an indexed set

I have a Pyomo model that has a sparse set of values but I get the error Cannot index a component with an indexed set when I try to index a binary variable according to this sparse set. For a simplified example:

model = ConcreteModel()

model.S = Set([1, 4, 6])
model.V = Var(model.S, within=Binary)
Solution

  • The line

    model.S = Set([1, 4, 6])

    creates an Indexed Set: that is a Set of 3 Sets, each one of which is empty (Pyomo treats positional arguments as indexing sets - just like in your comment about Var([1,3,5], within-Binary)). As it does not make sense to index something by a set-of-sets, you get the exception "Cannot index a component with an indexed set".

    In your case, it looks like you want a single set S that has three values. The correct syntax is:

    model.S = Set(initialize=[1, 4, 6])
model.V = Var(model.S, within=Binary)