I would like to color the background of each day in calendar according to the number of events in my org-agenda. The idea is to have a quick and visual idea of what are the busiest days. The code from How to highlight weekend days in Emacs calendar? might be a good start and I would need to write a function that, given a date, returns the number of scheduled event from my org-agenda/diary (I use org-diary) and set the face to
I already wrote a Python code for doing more or less the same in the terminal (see Yearly calendar view of agenda (with colored background) but my elisp is not so good.