On my machine, your reduce example (I actually wrote that myself as my first try) runs marginally slower than my loop example. I don't know why you're getting such weird numbers. Your areduce example is worst of all at 74072 on my machine.
On Dec 22, 12:39 pm, David Powell <djpow...@djpowell.net> wrote: > Hi, > > > I have a piece of code, and I'd like to see how fast it can be. > > (defn count-num-chars [^String s] > > (loop [s s acc 0] > > (if (seq s) > > (recur (rest s) (if (= (first s) \space) acc (inc acc))) > > acc))) > > I get an average of 46928 for this. > > But for the straightforward option of reduce: > > (defn count-num-chars3 [^String s] > (reduce (fn [acc c] (if (= c \space) acc (inc acc))) 0 s)) > > I get an average of 27424. Cool! So writing it the nicest way, is > also faster. > > I tend to avoid spamming .charAt even in Java for things like this, > and often find converting to an array first to be faster, like this: > > (defn count-num-chars4 [^String s] > (let [as (.toCharArray s)] > (areduce as idx acc 0 (if (= (int (aget as idx)) (int \space)) acc (inc > acc))))) > > I get an average of 3631. > > (needed to cast the char to int there, else clojure seems to hit > reflection problems) > > -- > Dave -- 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 Note that posts from new members are moderated - please be patient with your first post. 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
