Created
February 28, 2013 03:30
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random string (clojure)
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| (defn rand-str [len] | |
| (apply str (take len (repeatedly #(char (+ (rand 26) 65)))))) |
great thanks!
great thanks!
Great thanks!
Came in really handy when needed and saved valuable time. Thanks!
By using a list comprehension, I could improve times by ~30%
(defn rand-str [len]
(apply str
(for [i (range len)]
(char (+ (rand 26) 65))))))
user=> (defn bench [len]
#_=> (time (rand-str-old len))
#_=> (time (rand-str len))
#_=> nil)
#'user/bench
user=> (bench 1e+9)
"Elapsed time: 149173.812436 msecs"
"Elapsed time: 109004.200836 msecs"
nil
great thanks!
Appreciate it!
great thanks!
just for fun, and supporting lowercase and capital letters:
(defn rand-letter-str
[len]
(transduce
(map (fn [_]
(let [rnd (rand-int 52)]
(char (+ (mod rnd 26)
(int (if (< rnd 26) \a \A)))))))
str
""
(range len)))
Because we can, here's two more ways to do it and a bench to check the speed for all above mentioned and the two others.
Take your pick :)
(let [rep-rand-str (fn [len] (apply str (take len (repeatedly #(char (+ (rand 26) 65))))))
for-rand-str (fn [len] (apply str (for [i (range len)] (char (+ (rand 26) 65)))))
loop-rand-str (fn [len] (loop [len len r []] (if (< 0 len) (recur (dec len) (conj r (char (+ (rand 26) 65)))) (apply str r))))
reduce-rand-str (fn [len] (apply str (reduce (fn [r l] (conj r (char (+ (rand 26) 65)))) [] (range len))))
transduce-rand-str (fn [len] (transduce (map (fn [_] (let [rnd (rand-int 52)] (char (+ (mod rnd 26) (int (if (< rnd 26) \a \A))))))) str "" (range len)))
bench (fn [len times]
(time (dotimes [_ times] (rep-rand-str len)))
(time (dotimes [_ times] (for-rand-str len)))
(time (dotimes [_ times] (loop-rand-str len)))
(time (dotimes [_ times] (reduce-rand-str len)))
(time (dotimes [_ times] (transduce-rand-str len)))
nil)]
(bench 1e+5 100))
"Elapsed time: 2171.6456 msecs"
"Elapsed time: 1041.4757 msecs"
"Elapsed time: 1352.2245 msecs"
"Elapsed time: 1268.5602 msecs"
"Elapsed time: 121711.7105 msecs"
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great thanks!