setup_problem.py

import json
import uuid
from pathlib import Path
from random import randint, seed

MAX_CAPACITY = 250
NB_ITEMS = 50
MAX_WEIGHT = 50
MAX_PROFIT = 50


def parameter_knapsack(
        max_capacity=MAX_CAPACITY,
        nb_items=NB_ITEMS,
        max_weight=MAX_WEIGHT,
        max_profit=MAX_PROFIT,
        parameters_seed=None,
        output_dir="parameters"
):
    # Setting random seed
    if parameters_seed is not None:
        seed(parameters_seed)

    capacity = randint(a=int(max_capacity/2), b=max_capacity)

    items = [
        {
            "weight": randint(a=int(max_weight/2), b=max_weight),
            "profit": randint(a=1, b=max_profit)
        }
        for _ in range(nb_items)
    ]

    parameters_id = f"knapsack_{capacity}_{nb_items}_{uuid.uuid4().hex[:8]}"
    parameters = {
        "id": parameters_id,
        "capacity": capacity,
        "items": items,
        "metadata": {
            "nb_items": nb_items,
            "seed": parameters_seed
        },
    }
    output_path = Path(output_dir)

    # Store parameters for loading
    json_file = output_path / f"{parameters_id}.json"
    with open(json_file, "w") as f:
        json.dump(parameters, f, indent=2)
    return json_file


def batch_generate(
        n_instances,
        max_capacity=None,
        nb_items=None,
        max_weight=None,
        max_profit=None,
        parameters_seed=None,
        output_dir=None
):
    for i in range(n_instances):
        # Unique seed per instance for reproducibility
        instance_seed = parameters_seed + i if parameters_seed is not None else None

        parameter_knapsack(
            max_capacity=max_capacity if max_capacity is not None else MAX_CAPACITY,
            nb_items=nb_items if nb_items is not None else NB_ITEMS,
            max_weight=max_weight if max_weight is not None else MAX_WEIGHT,
            max_profit=max_profit if max_profit is not None else MAX_PROFIT,
            parameters_seed=instance_seed,
            output_dir=output_dir if output_dir is not None else None
        )


def load_parameters(filepath):
    with open(filepath, "r") as f:
        return json.load(f)