Thanks for the explanation. I did see in the docs that the map function can take multiple collections, but I guess I did not quite understand it. Your explanation really helps illustrate how it works. My Java version of this is probably around 30 lines with several branches/execution paths and variables as opposed to a 1-line clojure version that is free of branching and variables. I'm hooked ;-) On Thu, Apr 8, 2010 at 1:38 PM, James Reeves <weavejes...@googlemail.com>wrote:
> On Apr 8, 1:13 pm, John Sanda <john.sa...@gmail.com> wrote: > > [ > > [1 2 3] > > [2 5 1] > > [4 2 6] > > ] > > > > I am comparing the values in each of the columns, so the result should be > [4 > > 5 6] where the first element represents the largest value in the first > > column, the second element represents the largest value in the second > > column, etc. > > The `map` function allows you to specify more than one collection. > With multiple collections, the mapping function is passed an argument > for each collection. So: > > (map + [1 2 3] [4 5 6]) > => ((+ 1 4) (+ 2 5) (+ 3 6)) > => (5, 7, 9) > > By combining this with `apply` and `max`, you can find the maximum > value of each column: > > (defn max-columns [coll] > (apply map max coll)) > > If we pass your vector to max-columns: > > (max-columns [[1 2 3] [2 5 1] [4 2 6]]) > => (apply map max [[1 2 3] [2 5 1] [4 2 6]]) > => (map max [1 2 3] [2 5 1] [4 2 6]) > => ((max 1 2 4) (max 2 5 2) (max 3 1 6)) > => (4 5 6) > > - James > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com<clojure%2bunsubscr...@googlegroups.com> > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > > To unsubscribe, reply using "remove me" as the subject. > -- - John -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
