Now let’s cover the only macro we need to operate on rows: @subset It follows the same principes we’ve seen so far with , except that the operation must return a boolean variable for row selection.

As you can see, @subset has also a vectorized variant @rsubset. Sometimes we want to mix and match vectorized and non-vectorized function calls. For instance, suppose that we want to filter out the grades above the mean grade:

also supports multiple operations inside a begin ... end statement: