I’ve been using R or its predecessors for about 30 years, so I tend to I know a lot about R, but I don’t necessarily know how to use modern R tools. Lately, I’ve been teaching my students the tidyverse approach to data analysis, which means that I need to unlearn some old approaches and to re-learn them using new tools. But old dogs and new tricks… Yesterday, I was teaching a class where I needed to extract some rows of a data …