Re: [Chicken-users] Good way to code the equivalent to this?

[Elf]

i got almost the same time as with my previous (incorrect) method by using a 
single hash table and an alist instead of a hash for the inner structure. 
memory usage isnt so good though. :(

using a sparse multiple-alist structure seems to work nicely in small space
and good time.  i can post the code if interested.

-elf

On Sun, 24 Aug 2008, Jim Ursetto wrote:

> Note that your solution effects a mapping of x -> y, not from x -> y
> -> #t.  That gets the job accomplished correctly, but doesn't reflect
> the original Perl code.  For a fair comparison, you have to change the
> perl code to match, and then it runs in 1/3 of the memory and 1/2 the
> time of the original perl code.
>
> This is what I mean concretely:
>
> print "Filling the array with 250000 entries.\n";
> foreach $n (0 .. 250000) {
> $x = int(rand(500000));
> $y = int(rand(500000));
> $a{$x} = $y;                     # change to one-level hash
> }
>
> print "Reading from the array 10000 times\n";
> $hits=0;
> foreach $n (0 .. 10000) {
> $x = int(rand(500000));
> $y = int(rand(500000));
> if (exists $a{$x} and $a{$x} == $y) {  # quell warning on undef
>   $hits++;
> }
> }
>
> print "Done (hits $hits)\n";
>
> On Sun, Aug 24, 2008 at 5:56 AM, Elf <address@hidden> wrote:
> > for an improvement in time (surprisingly), use
> >
> > (define a
> >    (alist->hash-table
> >        (let loop ((i   0)
> >                   (r   '()))
> >            (if (fx= 250000 i)
> >                r
> >                (loop (fx+ 1 i)
> >                      (cons (cons (random 500000) (random 500000)) r))))
> >        =))