Indicator constraint not working as expected

Ongoing

Michael Smith

September 28, 2021 10:19

• 
• 

Hi,

I have an array of variables that I want to count the number of non zero elements. I have tried using an indicator variable to achieve this. However, the indicator variable is not being applied and is always 0. Below is some sudo code to show what I am trying to achieve. Is this the best way to count non-zeros? If so any idea why this may not be working?

Thanks

qty = 100
x_vars = []
x_abs_qty_vars = []
for i in range(10)"
    x = m.addVar(
        vtype=GRB.BINARY,
        name=f"x")

    x_qty = m.addVar(
        lb=min(0, qty), ub=max(0, qty),
        vtype=GRB.CONTINUOUS,
        name=f"x_qty")

    x_abs_qty = m.addVar(
        lb=0, ub=abs(qty),
        vtype=GRB.CONTINUOUS,
        name=f"x_abs_qty")

    m.addGenConstrAbs(
        allocated_abs_qty, allocated_qty,
        name=f"x_abs_qty_constr")

    m.addConstr((allocated == 1) >>
                (allocated_abs_qty >= 1))
    x_vars.append(x)
    x_abs_qty_vars.append(x_abs_qty)

n_non_zero = gp.quicksum(x_vars)

0

• Official comment

  

  Simranjit Kaur

  • Gurobi Staff

  December 06, 2024 00:25

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