Re: [Ocaml-lib-devel] ExtArray?

[Amit D. <ami...@gm...>]

Hi,

Did you do any benchmarks?  I did a quick, creating 10000 arrays of random
size between 0-1000 (a couple preliminary tests of size 0-10000 elements
gave a similar trend).  On average,  I get results like:

byte code:
jones 6.9 (from CVS)
hurt 7.2 (from email)
skaller  5.8 (list with remembered size - see below)

native code:
jones  0.82
hurt  0.80
skaller 0.72

So, it would seem that the version which uses lists + length as an
intermediate representation is the fastest.  Caveat: I probably didn't run
it long enough/with large enough arrays to test the effects of garbage
collection. Brian's version might be better in these cases, but that may
require more in-depth testing.  But Max's version is much simpler! :)

I think these results suggest that it may make a lot of sense to have
find_all return a list.  (As Max suggested, perhaps a common function calle=
d
by both find_all and filter, which returns list * length).

-Amit

(Code for skaller below)

let filter f a =3D
    let result =3D ref [] in
    let n =3D ref 0 in
        Array.iter
            (fun x ->
                if f x then begin
                    result :=3D x :: !result;
                    incr n
                end)
            a;
    match !result with
    | []    ->    [| |]
    | x::xs    ->
        let filtered =3D Array.create !n x in
        let rec fill i =3D function
        | []    -> filtered
        | x::xs -> filtered.(i) <- x; fill (i+1) xs
        in
            fill 1 xs;;

On 11/25/05, Richard Jones <ri...@an...> wrote:
>
>
> I've changed the implementation of Array.filter to use BitSets at your
> suggestion.  The version using the actual BitSet type is quite a bit
> shorter than your version.
>
> I've also implemented Array.partition along the same lines.
>
> Rich.
>
> --
> Richard Jones, CTO Merjis Ltd.
> Merjis - web marketing and technology - http://merjis.com
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