Mercurial > lasercutter
annotate src/clojure/contrib/greatest_least.clj @ 10:ef7dbbd6452c
added clojure source goodness
| author | Robert McIntyre <rlm@mit.edu> |
|---|---|
| date | Sat, 21 Aug 2010 06:25:44 -0400 |
| parents | |
| children |
| rev | line source |
|---|---|
| rlm@10 | 1 (ns |
| rlm@10 | 2 ^{:author "Vincent Foley", |
| rlm@10 | 3 :doc "Various functions for finding greatest and least values in a collection"} |
| rlm@10 | 4 clojure.contrib.greatest-least) |
| rlm@10 | 5 |
| rlm@10 | 6 (defn- boundary |
| rlm@10 | 7 [cmp-fn f & args] |
| rlm@10 | 8 (when args |
| rlm@10 | 9 (reduce (fn [a b] (if (cmp-fn (compare (f b) (f a))) |
| rlm@10 | 10 b |
| rlm@10 | 11 a)) args))) |
| rlm@10 | 12 |
| rlm@10 | 13 (defn greatest-by |
| rlm@10 | 14 "Return the argument for which f yields the greatest value." |
| rlm@10 | 15 [f & args] |
| rlm@10 | 16 (apply boundary pos? f args)) |
| rlm@10 | 17 |
| rlm@10 | 18 (defn greatest |
| rlm@10 | 19 "Return the greatest argument." |
| rlm@10 | 20 [& args] |
| rlm@10 | 21 (apply greatest-by identity args)) |
| rlm@10 | 22 |
| rlm@10 | 23 (defn least-by |
| rlm@10 | 24 "Return the argument for which f yields the smallest value." |
| rlm@10 | 25 [f & args] |
| rlm@10 | 26 (apply boundary neg? f args)) |
| rlm@10 | 27 |
| rlm@10 | 28 (defn least |
| rlm@10 | 29 "Return the smallest element." |
| rlm@10 | 30 [& args] |
| rlm@10 | 31 (apply least-by identity args)) |
| rlm@10 | 32 |
| rlm@10 | 33 |
| rlm@10 | 34 (defn- boundary-all |
| rlm@10 | 35 [cmp-fn f & args] |
| rlm@10 | 36 (when args |
| rlm@10 | 37 (reduce (fn [a b] |
| rlm@10 | 38 (if (nil? a) |
| rlm@10 | 39 (cons b nil) |
| rlm@10 | 40 (let [x (compare (f b) (f (first a)))] |
| rlm@10 | 41 (cond (zero? x) (cons b a) |
| rlm@10 | 42 (cmp-fn x) (cons b nil) |
| rlm@10 | 43 :else a)))) |
| rlm@10 | 44 nil |
| rlm@10 | 45 args))) |
| rlm@10 | 46 |
| rlm@10 | 47 (defn all-greatest-by |
| rlm@10 | 48 "Return all the elements for which f yields the greatest value." |
| rlm@10 | 49 [f & args] |
| rlm@10 | 50 (apply boundary-all pos? f args)) |
| rlm@10 | 51 |
| rlm@10 | 52 (defn all-greatest |
| rlm@10 | 53 "Returns all the greatest elements." |
| rlm@10 | 54 [& args] |
| rlm@10 | 55 (apply all-greatest-by identity args)) |
| rlm@10 | 56 |
| rlm@10 | 57 (defn all-least-by |
| rlm@10 | 58 "Return all the elements for which f yields the least value." |
| rlm@10 | 59 [f & args] |
| rlm@10 | 60 (apply boundary-all neg? f args)) |
| rlm@10 | 61 |
| rlm@10 | 62 (defn all-least |
| rlm@10 | 63 "Returns all the least elements." |
| rlm@10 | 64 [& args] |
| rlm@10 | 65 (apply all-least-by identity args)) |