Well, I guess the second number is a bit misleading. Of course, when you're iterating the time taken will depend on the (expected) presence and position of the target in the list. Still, the order is the same even in the worst case:
user> (time (dotimes [_ 100000] (some #(= 100 %) (range 100)))) "Elapsed time: 2213.944 msecs" On Feb 26, 10:02 am, Jason Wolfe <jawo...@berkeley.edu> wrote: > Hi Mark, > > The results will depend on the objects you are comparing. If you need > to search through the list multiple times, converting to a set once is > almost certainly going to be faster. But, if you're just doing it > once, iterating will usually be much faster: > > user> (time (dotimes [_ 100000] (contains? (set (range 100)) 10))) > "Elapsed time: 7708.336 msecs" > > user> (time (dotimes [_ 100000] (some #(= 10 %) (range 100)))) > "Elapsed time: 291.474 msecs" > > user> (time (let [s (set (range 100))] (dotimes [_ 100000] (contains? > s 10)))) > "Elapsed time: 27.978 msecs" > > In a simple test I get similar results for strings too... what > conditions were you testing under? > > -Jason > > On Feb 26, 7:53 am, Mark Volkmann <r.mark.volkm...@gmail.com> wrote: > > > I thought for sure it would be faster to use "some" to determine > > whether an item was in a list rather than convert the list to a set > > and then use "contains?", but it turns out I was wrong. The latter > > approach takes about 1/3 to 1/2 the time! This is the case even when > > the list contains 100 items. Of course I realize that if this is a > > commonly needed operation for a particular collection, it's better to > > use a set instead of a list in the first place. > > > (def stooges (list "Moe" "Larry" "Curly")) > > (time (some #(= % "Curly") stooges)) > > (time (contains? (set stooges) "Curly")) > > > -- > > R. Mark Volkmann > > Object Computing, Inc. > > --~--~---------~--~----~------------~-------~--~----~ 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 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 -~----------~----~----~----~------~----~------~--~---
