jwidauer / cutsolver

Webservice to determine ideal cut placement on stocks

CutSolver

This API can be used to solve the common problem of finding the perfect placement of cuts for specified lengths. It seems like no other free service tackles this specific problem in an easy to use format, so this is my attempt.

This Solver is using ints exclusively, as there is no need for arbitrary precision yet. It also has no concept of units so you can use whatever you want. Try using mm instead of cm if you have fractions.

Nerd talk: This is the 2D "Cutting Stock Problem", which is NP-hard. It can be reduced to the Bin-Packing-Problem (BPP). No efficient algorithm exists to calculate a perfect solution in an acceptable timeframe, therefore brute force (perfect solution) is used for small jobs and a heuristic (fast solution) für larger ones. Don't be surprised if you get different results, many combinations have equal trimmings and are therefore seen as equally good.

Usage

This is a backend, see CutSolverFrontend for a human usable version.

Send POST-Requests to [localhost]/solve, see /docs for further informations.

The easiest (and advised) way to deploy this is by using Docker.

Docker Hub

Now with 100% more Multiarchitecture! Both linux/amd64 and linux/arm/v7 are currently supported, message me if you use another platform.

You don't need to checkout this repository, I am building images and pushing them to Docker Hub.

Download and start this container by using the provided docker-compose file or running: docker run [--rm -it] -p80:80 modischfabrications/cutsolver:latest.

Note: Replace latest with a version number if you depend on this interface, I can guarantee you that the interface will change randomly. It's not like I know what I'm doing, it's more like a learning curve.

Local build

1. Build and start this image using docker-compose up
2. wait a while for uvloop to build... (1000s)
3. See usage for interactions.

Developing

Feel free to contact me or make a pull-request if you want to participate.

Install pre-commit with pre-commit install && pre-commit install -t pre-push.

Change version number in:

1. main.py:version
2. git tag
3. Dockerfile?

This should be checked and or fixed by pre-commit, execute pre-commit run --all-files --hook-stage push to run manually.

Prebuild docker images

Docker Hub should be updated automatically by Travis, but it's a broken mess (#16).

Installation of a multibuilder (once): check "experimental features" in Docker Desktop.

docker buildx inspect multibuilder --bootstrap

Update manually with the following steps (replace with version, e.g. v0.3.7):

docker login -u modischfabrications
docker buildx build --platform linux/amd64,linux/arm/v7 \
    -t modischfabrications/cutsolver:<VERSION> \
    -t modischfabrications/cutsolver:latest --push .

Wait a while for uvloop to build (~1000s) and all layers to be pushed (~400s).

Check https://hub.docker.com/repository/docker/modischfabrications/cutsolver to see results.

Want to check the size prior to pushing it? Rebuild the docker image with docker-compose up --build and check uncompressed image size with docker-compose images.

Dependencies

Everything should be handled by Docker

This project uses:

• pipenv: library management
• FastAPI: easy webservice (this includes much more!)
• httpie: curl-like for docker healthcheck

External links

https://scipbook.readthedocs.io/en/latest/bpp.html