In Clojure we can use the rand-nth function to get a single random element from a sequence. To get multiple items based on random probability for each item we use the function random-sample. We must set the probability that determines for each item if it is in the result or not.
In the following example code we use rand-nth function:
1 2 3 4 5 6 7 8 9 10 | (ns mrhaki.seq.random (:require [clojure.test :refer [is]]));; We use the function rand-nth to get a ;; random element from a sequence collection.(is (contains? #{"Clojure" "Java" "Groovy"} (rand-nth ["Groovy", "Clojure", "Java"])));; We can use the rand-nth function with a map;; if we first turn it into a sequence.(is (contains? #{[:a 1] [:b 2]} (rand-nth (seq {:a 1 :b 2})))) |
This next example shows how we can use the random-sample function:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | (ns mrhaki.seq.random (:require [clojure.test :refer [is]]));; Using random-sample each item is in the;; result based on the random probability of the;; probability argument. ;; When probability is 1 all items are returned.(is (= ["Clojure" "Groovy" "Java"] (random-sample 1.0 ["Clojure" "Groovy" "Java"])));; When proability is 0 no item is in the result.(is (empty? (random-sample 0 ["Clojure" "Groovy" "Java"])));; Any other value between 0 and 1 will return different;; results for each invocation of the random-sample function.(def samples (random-sample 0.4 ["Clojure" "Groovy"]))(is (or (empty? samples) (= ["Clojure" "Groovy"] samples) (= ["Clojure"] samples) (= ["Groovy"] samples))) |
Written with Clojure 1.10.1
