I wrote an post with a short and (hopefully) understandable implementation a while ago: https://terbium.io/2018/11/wave-function-collapse/ https://terbium.io/20

I wrote an post with a short and (hopefully) understandable implementation a while ago: https://terbium.io/2018/11/wave-function-collapse/ https://terbium.io/2018/11/wave-function-collapse/. There's a Jupyter notebook you can download at the bottom of the page.