in reply to Re: Re3: Anyone use "xor" in conditionals?
in thread Anyone use "xor" in conditionals?

++ BrowserUK for thinking like i do. :) how about this little gem from Net::Netmask...

       sort_by_ip_address       This function is included in "Net::Netmask"
                                simply because there doesn't seem to be a bet-
                                ter place to put it on CPAN.  It turns out
                                that there is one method for sorting dotted-
                                quads ("a.b.c.d") that is faster than all the
                                rest.  This is that way.  Use it as
                                "sort_by_ip_address(@list_of_ips)".

sub sort_by_ip_address
{
    return sort { pack("C4",split(/\./,$a)) cmp pack("C4",split(/\./,$
+b)) } @_
}

[download]

which has to be about the worst possible.

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Re6: Anyone use "xor" in conditionals?
by dragonchild (Archbishop) on Jul 15, 2003 at 13:49 UTC
    which has to be about the worst possible.

    Prove it.

    ------
    We are the carpenters and bricklayers of the Information Age.

    Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

    Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.

[reply]
      use Benchmark qw(cmpthese);

sub rbyte { int rand 256 }

my @unsorted;
for (1..10000) { push @unsorted, join '.', rbyte, rbyte, rbyte, rbyte 
+}

sub sort_by_ip_address
{
  return sort { pack("C4",split(/\./,$a)) cmp pack("C4",split(/\./,$b)
+) } @_
}

sub sort_faster
{
  return map {$_->[1]} sort {$a->[0] cmp $b->[0]} map {[(pack('C4',spl
+it(/\./,$_))), $_]} @_
}

my @sorted;
cmpthese( 10, {
    '  slow' => sub { @sorted = sort_by_ip_address(@unsorted) },
    'faster' => sub { @sorted = sort_faster(@unsorted) },
});
__END__
$ perl fastip.pl 
Benchmark: timing 10 iterations of  slow, faster...
      slow: 80 wallclock secs (40.79 usr +  0.00 sys = 40.79 CPU) @  0
+.25/s (n=10)
    faster: 15 wallclock secs ( 6.95 usr +  0.06 sys =  7.01 CPU) @  1
+.43/s (n=10)
       s/iter   slow faster
  slow   4.08     --   -83%
faster  0.701   482%     --

      [download]
[reply]
[d/l]

        I suspect that this will be roughly twice as fast as yours: 

        map { join ".", unpack "C*", $_ }
sort
map { pack "C*", split /\./, $_ }
@ips;

        [download]
        and Benchmark says... 
                  Rate   slow faster    tye
  slow 0.575/s     --   -75%   -83%
faster  2.34/s   307%     --   -32%
   tye  3.45/s   501%    48%     --

        [download]
        Drat, only 50% faster. (: Probably because the S. Transform is specially optimized these days.

        Full code in HTML comments at top of node so "download code" will fetch it for you.

                        - tye
[reply]
[d/l]
[select]
        Have you sent in the patch?

        ------
        We are the carpenters and bricklayers of the Information Age.

        Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

        Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.

[reply]

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