Programming in R can sometimes seem a bit tricky; the control flow and looping structures it has, are a bit more basic than in other languages. As many R functions are vectorized, the language actually has some features and functions; that mean we don't need to take the same low-level approach we may have learned in Python or other places. Instead, base R provides the apply functions to do the job of common looping tasks. These functions all have a loop inside them, meaning we don't need to specify the loop manually. In this recipe, we'll look at using some apply family functions with common data structures to loop over them and get a result. The common thread in all of the apply functions is that we have an input data structure that we're going to iterate over and some code (often wrapped in a function definition...