On 14 Feb 2010, at 13:20, ka wrote: > I'm trying to make a function which gives the n! permutations of a > vector of n things. Here is my first attempt : > > (defn permute > "Gives the n! permuations of the input vector of things" > [v] > (if (= 1 (count v)) (list [(v 0)]) > (loop [i 0 perm '()] > (if (= i (count v)) > perm > (let [s-v (into [] (concat (subvec v 0 i) (subvec v (inc i)))) > perm-s-v (permute s-v) > new-perms (map #(conj % (v i)) perm-s-v)] > (recur (inc i) (into perm new-perms))))))) > > 1:160 user=> (permute [1 2 3]) > ([2 1 3] [1 2 3] [3 1 2] [1 3 2] [3 2 1] [2 3 1]) > > How can I write this in a better fashion? In particular how do I make > this lazy?
Check out the source for clojure.contrib.combinatorics: http://richhickey.github.com/clojure-contrib/combinatorics-api.html -Steve -- 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
