diff --git a/knapsack-pyoptinterface/.devcontainer/devcontainer.json b/knapsack-pyoptinterface/.devcontainer/devcontainer.json new file mode 100644 index 0000000..6e965ed --- /dev/null +++ b/knapsack-pyoptinterface/.devcontainer/devcontainer.json @@ -0,0 +1,16 @@ +// For format details, see https://aka.ms/devcontainer.json. For config options, see the +// README at: https://github.com/devcontainers/templates/tree/main/src/go +{ + "name": "Python", + // Or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile + "image": "ghcr.io/nextmv-io/runtime/python:3.11", + "customizations": { + "vscode": { + "extensions": ["ms-python.debugpy", "ms-python.python"], + "settings": { + "python.defaultInterpreterPath": "python" + } + } + }, + "postCreateCommand": "pip install -r requirements.txt" +} diff --git a/knapsack-pyoptinterface/LICENSE b/knapsack-pyoptinterface/LICENSE new file mode 100644 index 0000000..2c27ec7 --- /dev/null +++ b/knapsack-pyoptinterface/LICENSE @@ -0,0 +1,201 @@ + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + + TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + + 1. 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We demonstrate this +by solving the knapsack problem using the [PyOptInterface][pyoptinterface] MIP +modeling interface. + +Knapsack is a classic combinatorial optimization problem. Given a collection of +items with a value and weight, our objective is to maximize the total value +without exceeding the weight capacity of the knapsack. + +The input defines a number of items which have an id to identify the item, a +weight and a value. Additionally there is a weight capacity. + +The most important files created are `main.py` and `input.json`. + +* `main.py` implements a MIP knapsack solver. +* `input.json` is a sample input file. + +Follow these steps to run locally. + +1. The packages listed in the `requirements.txt` will get bundled with the app + as defined in the `app.yaml` manifest. When working locally, make sure that + these are installed as well: + + ```bash + pip3 install -r requirements.txt + ``` + +1. Run the command below to check that everything works as expected: + + ```bash + python3 main.py -input input.json -output output.json -duration 30 + ``` + +1. A file `output.json` should have been created with the optimal knapsack + solution. + +## Mirror running on Nextmv Cloud locally + +Pre-requisites: Docker needs to be installed. + +To run the application locally in the same docker image as the one used on the +Nextmv Cloud, you can use the following command: + +```bash +cat input.json | docker run -i --rm \ +-v $(pwd):/app ghcr.io/nextmv-io/runtime/python:3.11 \ +sh -c 'pip install -r requirements.txt > /dev/null && python3 /app/main.py' +``` + +You can also debug the application by running it in a Dev Container. This +workspace recommends to install the Dev Container extension for VSCode. If you +have the extension installed, you can open the workspace in a container by using +the command `Dev Containers: Reopen in Container`. + +## Next steps + +* Open `main.py` and read through the comments to understand the model. +* Further documentation, guides, and API references about custom modeling and + deployment can also be found on our [blog](https://www.nextmv.io/blog) and on + our [documentation site](https://docs.nextmv.io). +* Need more assistance? Send us an [email](mailto:support@nextmv.io)! + +[highs]: https://highs.dev/ +[pyoptinterface]: https://github.com/metab0t/PyOptInterface diff --git a/knapsack-pyoptinterface/VERSION b/knapsack-pyoptinterface/VERSION new file mode 100644 index 0000000..45c7a58 --- /dev/null +++ b/knapsack-pyoptinterface/VERSION @@ -0,0 +1 @@ +v0.0.1 diff --git a/knapsack-pyoptinterface/app.yaml b/knapsack-pyoptinterface/app.yaml new file mode 100644 index 0000000..f0de77f --- /dev/null +++ b/knapsack-pyoptinterface/app.yaml @@ -0,0 +1,11 @@ +# This manifest holds the information the app needs to run on the Nextmv Cloud. +type: python +runtime: ghcr.io/nextmv-io/runtime/python:3.11 +# List all files/directories that should be included in the app. Globbing +# (e.g.: configs/*.json) is supported. +files: + - main.py +python: + # Packages the app depends on need to be listed in a requirements.txt file + # that is referenced here. All listed packages will get bundled with the app. + pip-requirements: requirements.txt diff --git a/knapsack-pyoptinterface/input.json b/knapsack-pyoptinterface/input.json new file mode 100644 index 0000000..98eee19 --- /dev/null +++ b/knapsack-pyoptinterface/input.json @@ -0,0 +1,60 @@ +{ + "items": [ + { + "id": "cat", + "value": 100, + "weight": 20 + }, + { + "id": "dog", + "value": 20, + "weight": 45 + }, + { + "id": "water", + "value": 40, + "weight": 2 + }, + { + "id": "phone", + "value": 6, + "weight": 1 + }, + { + "id": "book", + "value": 63, + "weight": 10 + }, + { + "id": "rx", + "value": 81, + "weight": 1 + }, + { + "id": "tablet", + "value": 28, + "weight": 8 + }, + { + "id": "coat", + "value": 44, + "weight": 9 + }, + { + "id": "laptop", + "value": 51, + "weight": 13 + }, + { + "id": "keys", + "value": 92, + "weight": 1 + }, + { + "id": "nuts", + "value": 18, + "weight": 4 + } + ], + "weight_capacity": 50 +} diff --git a/knapsack-pyoptinterface/knapsack-highspy.code-workspace b/knapsack-pyoptinterface/knapsack-highspy.code-workspace new file mode 100644 index 0000000..3fd4af0 --- /dev/null +++ b/knapsack-pyoptinterface/knapsack-highspy.code-workspace @@ -0,0 +1,27 @@ +{ + "folders": [{ + "path": "." + }], + "launch": { + "configurations": [{ + "name": "Python: Module", + "type": "debugpy", + "request": "launch", + "module": "main", + "justMyCode": true, + "args": [ + "-input", + "input.json", + "-output", + "output.json", + "-duration", + "5" + ] + }] + }, + "extensions": { + "recommendations": [ + "ms-vscode-remote.remote-containers", + ] + } +} diff --git a/knapsack-pyoptinterface/main.py b/knapsack-pyoptinterface/main.py new file mode 100644 index 0000000..83b93c5 --- /dev/null +++ b/knapsack-pyoptinterface/main.py @@ -0,0 +1,152 @@ +""" +Template for working with the pyoptinterface library. +""" + +import argparse +import json +import sys +import time +from importlib.metadata import version +from typing import Any + +import pyoptinterface as poi +from pyoptinterface import highs + + +def main() -> None: + """Entry point for the template.""" + + parser = argparse.ArgumentParser(description="Solve problems with the pyoptinterface library.") + parser.add_argument( + "-input", + default="", + help="Path to input file. Default is stdin.", + ) + parser.add_argument( + "-output", + default="", + help="Path to output file. Default is stdout.", + ) + parser.add_argument( + "-duration", + default=30, + help="Max runtime duration (in seconds). Default is 30.", + type=int, + ) + args = parser.parse_args() + + # Read input data, solve the problem and write the solution. + input_data = read_input(args.input) + + log("Solving knapsack problem:") + log(f" - items: {len(input_data.get('items', []))}") + log(f" - capacity: {input_data.get('weight_capacity', 0)}") + log(f" - max duration: {args.duration} seconds") + + solution = solve(input_data, args.duration) + write_output(args.output, solution) + + +def solve(input_data: dict[str, Any], duration: int) -> dict[str, Any]: + """Solves the given problem and returns the solution.""" + + start = time.time() + + # Creates the solver. + model = highs.Model() + + # Initializes the linear sums. + weights = 0.0 + values = 0.0 + + # Creates the decision variables and adds them to the linear sums. + items = [] + for item in input_data["items"]: + item_variable = model.add_variable( + lb=0.0, + ub=1.0, + domain=poi.VariableDomain.Integer, + name=item["id"], + ) + items.append({"item": item, "variable": item_variable}) + weights += item_variable * item["weight"] + values += item_variable * item["value"] + + # This constraint ensures the weight capacity of the knapsack will not be + # exceeded. + model.add_linear_constraint( + expr=weights, + sense=poi.ConstraintSense.LessEqual, + rhs=input_data["weight_capacity"], + name="weight_capacity", + ) + + # Sets the objective function: maximize the value of the chosen items. + status = model.set_objective( + expr=values, + sense=poi.ObjectiveSense.Maximize, + ) + + # Solves the problem. + model.optimize() + status = model.get_model_attribute(poi.ModelAttribute.TerminationStatus) + + # Determines which items were chosen. + chosen_items = [item["item"] for item in items if model.get_value(item["variable"]) > 0.9] + + # Creates the statistics. + statistics = { + "result": { + "custom": { + "constraints": model.number_of_constraints(type=poi.ConstraintType.Linear), + "variables": model.number_of_variables(), + "status": str(status), + }, + "value": sum(item["value"] for item in chosen_items), + }, + "run": { + "duration": time.time() - start, + "version": version("pyoptinterface"), + }, + "schema": "v1", + } + + return { + "solutions": [{"items": chosen_items}], + "statistics": statistics, + } + + +def log(message: str) -> None: + """Logs a message. We need to use stderr since stdout is used for the + solution.""" + + print(message, file=sys.stderr) + + +def read_input(input_path: str) -> dict[str, Any]: + """Reads the input from stdin or a given input file.""" + + input_file = {} + if input_path: + with open(input_path, encoding="utf-8") as file: + input_file = json.load(file) + else: + input_file = json.load(sys.stdin) + + return input_file + + +def write_output(output_path: str, output: dict[str, Any]) -> None: + """Writes the output to stdout or a given output file.""" + + content = json.dumps(output, indent=2) + if output_path: + with open(output_path, "w", encoding="utf-8") as file: + file.write(content + "\n") + else: + print(content) + + +if __name__ == "__main__": + main() diff --git a/knapsack-pyoptinterface/requirements.txt b/knapsack-pyoptinterface/requirements.txt new file mode 100644 index 0000000..fd9e163 --- /dev/null +++ b/knapsack-pyoptinterface/requirements.txt @@ -0,0 +1,5 @@ +# pyoptinterface package with the Highs solver. +pyoptinterface[highs]==0.2.6 + +# Other packages. +nextmv==0.9.0