The R package dplyr has some attractive features; some say, this packkage revolutionized their workflow. At any rate, I like it a lot, and I think it is very helpful. In this post, I would like to share some useful (I hope) ideas (“tricks”) on filter, one function of dplyr. This function does what the name suggests: it filters rows (ie., observations such as persons). The addressed rows will be kept; the rest of the rows will be …