In addition to the functional shuffle thread (can't seem to post to that one anymore, might be too old?), I've written a lazy shuffle. Not sure if it is the best way to write it, but I needed a lazy shuffle primarily because I wanted to randomly pair a few agents from a large vector of agents without agents occurring one more than once.
http://groups.google.com/group/clojure/browse_thread/thread/180842eb58c58370/0e19ab338452c64f?tvc=2&q=shuffle#0e19ab338452c64f (defn lazy-shuffle [coll] (let [rand-pos (rand-int (count coll)) [prior remainder] (split-at rand-pos coll)] (lazy-cons (nth coll rand-pos) (lazy-shuffle (concat prior (rest remainder)))))) user=> (time (take 50 (lazy-shuffle (range 10000)))) "Elapsed time: 0.246 msecs" user=> (time (take 50 (shuffle-java (range 10000)))) "Elapsed time: 0.573 msecs" (defn frequencies "Returns a map from distinct items in coll to the number of times they appear." [coll] (reduce (fn [counts x] (merge-with + counts {x 1})) {} coll)) (frequencies (map (fn [n] (take 3 (lazy-shuffle (list 1 2 3)))) (range 1000000))) {(3 1 2) 166687, (1 2 3) 166126, (1 3 2) 167246, (3 2 1) 166918, (2 3 1) 166687, (2 1 3) 166336} --~--~---------~--~----~------------~-------~--~----~ 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 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 -~----------~----~----~----~------~----~------~--~---
