(Don't read the title, which belongs to the categories how to read a book and remember everything / how to learn a programming language in three days / how to loose weight by doing this five minutes per day... What follows is a seed. It needs you and your effort to grow. With diligence and luck, you might thank me for the flower later...)
Here is a glimpse into functional programming in R for the future me.
Filter selects a subset of a sequence based on a predicate.