gistfile1.clj

(require '[clojure.java.io :as io]
         '[clojure.string :as s])

(defn bench [filename f]
  (with-open [r (io/reader filename)]
    (->> (line-seq r)
         (map f)
         (group-by first))))

(defn f1 [line]
  (s/split line #","))

(defn f2 [^String line]
  (let [a (.split line ",")]
    [(aget a 0) (aget a 1)]))

(defn f3 [^String line]
  (let [i (.indexOf line ",")]
    [(subs line 0 i) (subs line (inc i))]))

(defn f4 [^String line]
  (let [i (.indexOf line \,)]
    [(.substring line 0 i) (.substring line (inc i))]))

(comment

user=> (dotimes [_ 10] (time (bench "word-pairs.txt" f1)))
"Elapsed time: 526.227394 msecs"
"Elapsed time: 702.749791 msecs"
"Elapsed time: 562.34146 msecs"
"Elapsed time: 698.198075 msecs"
"Elapsed time: 541.922056 msecs"
"Elapsed time: 530.039631 msecs"
"Elapsed time: 794.938614 msecs"
"Elapsed time: 535.111616 msecs"
"Elapsed time: 713.351931 msecs"
"Elapsed time: 544.983888 msecs"
nil
user=> (dotimes [_ 10] (time (bench "word-pairs.txt" f2)))
"Elapsed time: 403.787892 msecs"
"Elapsed time: 662.57368 msecs"
"Elapsed time: 437.026249 msecs"
"Elapsed time: 642.806364 msecs"
"Elapsed time: 505.520853 msecs"
"Elapsed time: 594.884303 msecs"
"Elapsed time: 487.522537 msecs"
"Elapsed time: 409.583012 msecs"
"Elapsed time: 664.536535 msecs"
"Elapsed time: 429.284961 msecs"
nil
user=> (dotimes [_ 10] (time (bench "word-pairs.txt" f3)))
"Elapsed time: 415.879649 msecs"
"Elapsed time: 427.029762 msecs"
"Elapsed time: 601.36135 msecs"
"Elapsed time: 353.645478 msecs"
"Elapsed time: 329.444905 msecs"
"Elapsed time: 345.413541 msecs"
"Elapsed time: 345.17908 msecs"
"Elapsed time: 582.244321 msecs"
"Elapsed time: 468.696403 msecs"
"Elapsed time: 597.620492 msecs"
nil
user=> (dotimes [_ 10] (time (bench "word-pairs.txt" f4)))
"Elapsed time: 595.612801 msecs"
"Elapsed time: 319.554858 msecs"
"Elapsed time: 317.883967 msecs"
"Elapsed time: 324.611155 msecs"
"Elapsed time: 339.650851 msecs"
"Elapsed time: 576.29066 msecs"
"Elapsed time: 434.755482 msecs"
"Elapsed time: 406.41307 msecs"
"Elapsed time: 579.015913 msecs"
"Elapsed time: 440.795543 msecs"
nil

average:
 f1: 614.9864456
 f2: 523.7526386
 f3: 446.6514981
 f4: 433.45843

)