##RAPM (Regularized Adjusted Plus Minus) #####By Daniel Myers (@DSMok1)
Several years ago I wrote A Review of Adjusted Plus Minus and Stabilization. Until now, I haven't actually attempted to calculate Regularized Adjusted Plus/Minus myself--while I understood the mathematical underpinnings, I haven't had the programming chops to actually do it.
After my work with Golf Ratings and a variety of other R projects, I think I can do this now.
The folks at Basketball Reference generously provided me with the already-parsed matchup files, saving my the hardest part of the programming.