Re: Fastest way to sort a list of integers into 0,1,2,3,-3,-2,-1

Hello haukex,

I have not seen others but here are two attempts. Anyway i bet on tybalt89's regex ;)

Discipulus => sub{
    my @list = @input;
    my @neg = sort {$a<=>$b} grep { $_ < 0 } @list;
    my @pos = sort {$a<=>$b} grep { $_ >= 0} @list;
    @list = (@pos,@neg);
    Compare(\@list,\@output) or die "@list" if DO_CHECK;
},
Discipulus2 => sub{
    my @list = sort {$a<=>$b} @input;
    push @list, shift @list until $list[0] >= 0;
    Compare(\@list,\@output) or die "@list" if DO_CHECK;
},
[download]

UPDATE what I first imagined was a sort block.. now after the right dose of spaghetti..

Discipulus3 => sub{
    my @list = sort {    
                     (( $a >= 0 and $b >= 0) 
                        or 
                     ($a < 0 and $b < 0  ))     ? 
                     $a<=>$b                    : 
                     $b<=>$a 
    } @input;
    Compare(\@list,\@output) or die "@list" if DO_CHECK;
},

#OUTPUT
               Rate  Discipulus Discipulus3 Discipulus2
Discipulus  46252/s          --        -14%        -46%
Discipulus3 53805/s         16%          --        -38%
Discipulus2 86380/s         87%         61%          --
[download]

There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

Comment on Re: Fastest way to sort a list of integers into 0,1,2,3,-3,-2,-1 Select or Download Code

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Re^2: Fastest way to sort a list of integers into 0,1,2,3,-3,-2,-1 by hdb (Monsignor) on Feb 05, 2019 at 17:03 UTC
I think your second version will be very slow if there are only negative numbers... ;) My version below is reasonably fast if there is no zero in the input, otherwise it fails: `hdb => sub { my @list = @input; @list = sort{$a*$b>0?$a<=>$b:$b<=>$a} @list; Compare(\@list,\@output) or die "@list" if DO_CHECK; },` [download]	[reply] [d/l]
Re^3: Fastest way to sort a list of integers into 0,1,2,3,-3,-2,-1 by Discipulus (Canon) on Feb 05, 2019 at 20:48 UTC
Hello hdb > version will be very slow if there are only negative numbers... ;) eh eh, you are right but the check does not slow it at all.. `Discipulus => sub{ my @list = sort {$a<=>$b} @input; if ($list[0] < 0 and $list[-1] > 0){ push @list, shift @list until $list[0] >= 0; } Compare(\@list,\@output) or die "@list" if DO_CHECK; },` [download] update: more test cases.. more checks! `Discipulus4 => q{ # https://www.perlmonks.org/?node_id=1229437 @list = sort {$a<=>$b} @list; if ($list[0] < 0 and $list[-1] >= 0) { push @list, shift @list until $list[0] >= 0 } },` [download] L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l] [select]
Re^3: Fastest way to sort a list of integers into 0,1,2,3,-3,-2,-1 by Tux (Canon) on Feb 06, 2019 at 10:58 UTC
You might not have run this with DO_CHECK on, as your lists sort like `1 2 3 4 5 0 -5 -4 -3 -2 -1`: Your `0` ends up in the middle instead of at the start. Enjoy, Have FUN! H.Merijn	[reply] [d/l] [select]
Re^4: Fastest way to sort a list of integers into 0,1,2,3,-3,-2,-1 by hdb (Monsignor) on Feb 06, 2019 at 11:13 UTC
I did, that's why I said it fails if there is a zero in the data. I am still thinking whether it can be saved in some way without extra checks for zero.	[reply]
Re^2: Fastest way to sort a list of integers into 0,1,2,3,-3,-2,-1 by Eily (Monsignor) on Feb 06, 2019 at 09:54 UTC
You missed one step in the last two. Instead of: `my @list = @input; @list = EXPR @list;` [download] You wrote: `my @list = EXPR @input;` [download] I don't know exactly how well perl optimizes, but there's a chance you're skipping one copy of the values, and one overwrite of the content of @list. On my computer your Discipulus2 rewritten to have the same format as the other tests is slightly slower than using first_index (like haukex did in the comments of his code, rather than the code itself?) with push and splice. ~~Now the "NoOverwrite" below is just your Discipulus2 where the absence of overwrite of @list is made explicit, and I have not been able to beat that one.~~ Edit: nope, that code was wrong. Fixed, and first_index wins: use warnings; use strict; use Benchmark 'cmpthese'; use constant DO_CHECK => 0; use if DO_CHECK, 'Data::Compare', qw/Compare/; use List::MoreUtils qw( first_index ); my @input = (-57..50,52,0); my @output = (0,0..50,52,-57..-1); use List::Util 'shuffle'; srand 123; @input = shuffle @input; cmpthese(DO_CHECK ? 1 : -2, { Eily => sub { # https://www.perlmonks.org/?node_id=1229411 my @list = @input; @list = sort { ~$b <=> ~$a } @list; Compare(\@list,\@output) or die "@list" if DO_CHECK; }, vr => sub { # https://www.perlmonks.org/?node_id=1229415 my @list = @input; @list = unpack 'i', pack 'I', sort { $a <=> $b } unpack 'I', pack 'i', @list; Compare(\@list,\@output) or die "@list" if DO_CHECK; }, Discipulus => sub{ # https://www.perlmonks.org/?node_id=1229419 my @list = @input; my @neg = sort {$a<=>$b} grep { $_ < 0 } @list; my @pos = sort {$a<=>$b} grep { $_ >= 0} @list; @list = (@pos,@neg); Compare(\@list,\@output) or die "@list" if DO_CHECK; }, Discipulus2 => sub{ # https://www.perlmonks.org/?node_id=1229419 my @list = @input; @list = sort {$a<=>$b} @list; push @list, shift @list until $list[0] >= 0; Compare(\@list,\@output) or die "@list" if DO_CHECK; }, NoOverwrite => sub{ # Actually Discipulus2 my @list = @input; my @sorted = sort {$a<=>$b} @list; # Don't overwrite push @sorted, shift @sorted until $sorted[0] >= 0; Compare(\@list,\@output) or die "@list" if DO_CHECK; }, Splice_FirstIdx => sub{ # Haukexish my @list = @input; @list = sort { $a <=> $b } @list; my $nb_neg = first_index { $_ >= 0 } @list; push @list, splice @list, 0, $nb_neg; Compare(\@list,\@output) or die "@list" if DO_CHECK; }, }); __END__ Rate Eily Discipulus vr NoOverwrite Discipulus2 S +plice_FirstIdx Eily 19851/s -- -55% -65% -68% -72% + -75% Discipulus 43848/s 121% -- -23% -28% -37% + -44% vr 56978/s 187% 30% -- -7% -18% + -28% NoOverwrite 61148/s 208% 39% 7% -- -12% + -22% Discipulus2 69804/s 252% 59% 23% 14% -- + -11% Splice_FirstIdx 78838/s 297% 80% 38% 29% 13% + -- [download]	[reply] [d/l] [select]


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