How to input a set into an OPL (Optimization Programming Language) model using Python

Question

In OPL for input set we are defining as given below:

tuple Damage_line_Nodes {
int value;
};

// Declare a set with a few tuples
{Damage_line_Nodes} Damage_line_Node = ...;

In python (we are trying to give the input to the OPL model using python code given below)

from doopl.factory import create_opl_model
# Data
Damage_Nodes = [
{8, 9, 12, 6, 19, 23, 24, 27, 30} 
]
my_set_list = list(Damage_Nodes)

model_path = "C:/Users/VCGA/opl/MEG/MEG.mod"

with create_opl_model(model=model_path) as opl:

opl.set_input("Damage_line_Node", Damage_Nodes)

opl.set_input('Damage_line_Node',my_set_list) 

opl.run()

Here's a explanation of the error we encountered -

 *** ERROR[GENERATE_001] at 795:25-42 C:/Users/VCGA/opl/MEG/MEG.mod: Cannot use type <value:int> for int.
*** ERROR[GENERATE_001] at 828:2-19 C:/Users/VCGA/opl/MEG/MEG.mod: Cannot use type <value:int> for int.
*** ERROR[GENERATE_001] at 837:2-19 C:/Users/VCGA/opl/MEG/MEG.mod: Cannot use type <value:int> for int.
Fatal Python error: Aborted

The error messages we are encountering indicate that there's a type mismatch in the OPL model between what is expected and what is being provided. Specifically, the OPL model is not accepting the type value:int as a valid type for int. Suggest that I use both OPL and Python to feed input to the OPL model using Python.

Alex Fleischer · Accepted Answer · 2024-08-21 17:56:25Z

0

You may use a list of tuples like in https://github.com/AlexFleischerParis/zoodocplex/blob/master/zoocallopl.py

Buses=[
        (40,500),
        (30,400)
        ]

# Create an OPL model from a .mod file
with create_opl_model(model="zootupleset.mod") as opl:
    # tuple can be a list of tuples, a pandas dataframe...
    opl.set_input("buses", Buses)

    # Generate the problem and solve it.
    opl.run()

In your case, turn

Damage_Nodes = [
{8, 9, 12, 6, 19, 23, 24, 27, 30} 
]

into

Damage_Nodes = [
(8,), (9,), (12,) , (6,) , (19,) , (23,) , (24,) , (27,) , (30,), 
]

answered Aug 21, 2024 at 17:56

Alex Fleischer

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1 Comment

Vikas Gautam Over a year ago

To provide input to the OPL model, I have defined tuple -- tuple Damage_line_Nodes { int value; }; // Declare a set with tuple {Damage_line_Nodes} Damage_line_Node = ...; And this set is used in constraint given below ----forall (s in Slot:!(s==24)){ forall (rc in repair_crew){ forall (n in Damage_line_Node){ StatusLine[rc][n][s+1]<=sum(t in 1..s)CrewPos[rc][n][t]/2; } } }. The error in OPL mode is --- Cannot use type <value:int> for int. Suggest me the corrections in OPL model.

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