Git-Heat-Map¹ does something similar to this. It's not open source but I found it easy re-implement the core algorithm² as a learning exercise in React.<p>¹- <a href="https://github.com/jmforsythe/Git-Heat-Map">https://github.com/jmforsythe/Git-Heat-Map</a><p>²- <a href="https://www.win.tue.nl/~vanwijk/stm.pdf" rel="nofollow">https://www.win.tue.nl/~vanwijk/stm.pdf</a>
this reminds me of <a href="https://github.com/nikolaydubina/go-cover-treemap">https://github.com/nikolaydubina/go-cover-treemap</a>