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Re: Efficiently sorting array by non-alpha strings

by Limbic~Region (Chancellor)
on Feb 20, 2004 at 16:09 UTC ( [id://330578]=note: print w/replies, xml ) Need Help??


in reply to Efficiently sorting array by non-alpha strings

knowmad,
I am assuming you want to sort first by locality type and second by title ASCIIBetically.
#!/usr/bin/perl use strict; use warnings; my @advocates = ( {fld_title => 'Rec1', fld_type => 'National'}, {fld_title => 'Rec2', fld_type => 'State' }, {fld_title => 'Rec3', fld_type => 'Local' } ); my %order = (LOCAL => 'A', STATE => 'B', NATIONAL => 'C'); my @sorted = map { $_->[0] } sort { $a->[1] cmp $b->[1] || $a->[2] cmp $b->[2] } map { [ $_ , $order{uc $_->{fld_type}}, $_->{fld_title} ] +} @advocates;
Cheers - L~R

I am waiting for tye to comment on my persistent use of the ST.

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Re: Re: Efficiently sorting array by non-alpha strings
by knowmad (Monk) on Feb 20, 2004 at 16:21 UTC

    L~R,

    I had not considered the secondary sort by title. Nice touch!

    I added your example into my benchmark tests which now include my original hack, Abigail's bucketsort example and yours (which looks to me like a Schwarztian Transform, no?). Yours takes the cake:

    Benchmark: timing 500000 iterations of bucketsort, sort, st... bucketsort: 1 wallclock secs ( 1.73 usr + 0.00 sys = 1.73 CPU) @ 28 +9017.34/s (n=500000) sort: 1 wallclock secs ( 0.90 usr + 0.00 sys = 0.90 CPU) @ 55 +5555.56/s (n=500000) st: 0 wallclock secs ( 0.66 usr + 0.00 sys = 0.66 CPU) @ 75 +7575.76/s (n=500000) Rate bucketsort sort st bucketsort 289017/s -- -48% -62% sort 555556/s 92% -- -27% st 757576/s 162% 36% --

    Thanks,

    -Wm
      knowmad,
      Actually, you can avoid the ST all together, which should be even faster.
      #!/usr/bin/perl use strict; use warnings; my @advocates = ( {fld_title => 'Rec1', fld_type => 'National'}, {fld_title => 'Rec2', fld_type => 'State' }, {fld_title => 'Rec3', fld_type => 'Local' } ); my %order = (LOCAL => 'A', STATE => 'B', NATIONAL => 'C'); my @sorted = sort { $order{uc $a->{fld_type}} cmp $order{uc $b->{fld_t +ype}} || $a->{fld_title} cmp $b->{fld_title} } @advocates; print "$_->{fld_title}\n" for @sorted;
      Cheers - L~R
        It's even faster if you avoid the sort block, using GRT:
        #!/usr/bin/perl use strict; use warnings; use Benchmark qw /timethese cmpthese/; our @advocates = map {{fld_title => 'Rec' . $_, fld_type => [qw /National State Local/] -> [ra +nd 3]}} 1 .. shift || 1000; our %order = (LOCAL => 'A', STATE => 'B', NATIONAL => 'C'); our %order_r = reverse %order; our (@limbic, @GRT); cmpthese -1 => { limbic => '@limbic = sort {$order {uc $a -> {fld_type}} cmp $order {uc $b -> {fld_type}} or $a -> {fld_title} cmp $b -> {fld_titl +e}} @advocates', GRT => '@GRT = map {{fld_title => substr ($_, 1), fld_type => $order_r {substr $_, 0, 1}} +} sort map {join "", $order {uc $_ -> {fld_type}}, $_ -> {fld_title}} @a +dvocates', }; my $limbic = join " " => map {$_ -> {fld_title}} @limbic; my $GRT = join " " => map {$_ -> {fld_title}} @GRT; die "Unequal\n" unless $limbic eq $GRT; __END__ Rate limbic GRT limbic 61.9/s -- -49% GRT 121/s 95% --
        It does lose the case of fld_type, but that's easily fixable.

        Abigail

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