Another one using for (defn col-widths [arr] (for [i (range (count arr))] (apply max (map #(nth % i) arr))))
On Thu, Apr 8, 2010 at 1:55 PM, John Sanda <john.sa...@gmail.com> wrote: > 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<clojure%2bunsubscr...@googlegroups.com> > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > -- 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
