6.3 Most frequent values

In the above example, the number of values is small (the seven weekdays); however, in many cases there can be many different values (for example, all different message subjects), many of which may not be very interesting – all we need to know is the top-10 of most frequently seen values.

This is fairly easy to achieve using mu:tabulate – to get the top-10 subjects⁸, we can use something like this:

(take
  (sort
    (mu:tabulate mu:subject)
    (lambda (a b) (> (cdr a) (cdr b))))
  10)

If this is not short enough, mu-guile offers a convenience procedure to do this: mu:top-n-most-frequent. For example, to get the top-10 people we sent mail to most often:

(mu:top-n-most-frequent mu:to 10 "maildir:/sent")

Can’t make it much easier than that!