Would it help to use an eq? hash and turn all of the strings into symbols (hopefully up front)? That might make the hashing part faster in the best-known function. (Also, you can use two accumulators in the for*/fold instead of one to avoid creating 'cons' cells but that seems unlikely to matter much.)
Robby On Fri, Jan 2, 2015 at 1:44 PM, Greg Hendershott <greghendersh...@gmail.com> wrote: > Although it can't hurt, I don't think `train` comes close to > dominating the time? > > Through the sophisticated profiling technique of commenting-out `or` > branches in `correct`, I got the sense that the third one is the > issue: > > > (define (correct m s) > (let ([best-known (λ (xs) (best-known m xs))]) > (or (best-known (list s)) > (best-known (edits1 s)) > (best-known (append-map edits1 (edits1 s))) <-- if reached, very slow > s))) > real 0m16.527s > user 0m14.554s > sys 0m1.859s > > > (define (correct m s) > (let ([best-known (λ (xs) (best-known m xs))]) > (or (best-known (list s)) > (best-known (edits1 s)) > (best-known (edits2 m s)) ;; what I posted yesterday > s))) > real 0m9.807s > user 0m9.463s > sys 0m0.266s > > > (define (correct m s) > (let ([best-known (λ (xs) (best-known m xs))]) > (or (best-known (list s)) > (best-known (edits1 s)) > ;; (best-known (edits2 m s)) ;; skip it entirely > s))) > real 0m2.074s > user 0m1.708s > sys 0m0.184s > > > p.s. `best-known` = combining `best` and `known` into a single pass for/fold: > > ;; Given a hash map and a list of words, returns > ;; one of the words with the highest frequency. > ;; Given an empty list returns #f > (define (best-known ht xs) > (car (for*/fold ([best (cons #f 0)]) > ([x (in-list xs)] > [v (in-value (hash-ref ht x #f))] ;; should default be 1? > #:when v) > (if (> v (cdr best)) (cons x v) best)))) > > ... which I thought might be faster but wasn't significant. > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
