By my count, 157 new packages stuck to CRAN in December. Below are my “Top 40” picks in ten categories: Computational Methods, Data, Finance, Machine Learning, Medicine, Science, Statistics, Time Series, Utilities and Visualization. This is the first time I have used the Medicine category. I am pleased that a few packages that appear to have clinical use made the cut. Also noteworthy in this month’s selection are the inclusion of four packages from the Microsoft Azure team (stuffing 41 packages into the “Top 40”), and some eclectic, but fascinating packages in the Science section.