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

by choroba (Archbishop)
on Feb 05, 2019 at 14:17 UTC ( #1229407=note: print w/replies, xml ) Need Help??


in reply to Fastest way to sort a list of integers into 0,1,2,3,-3,-2,-1

So first sort by signum, but zero go first, then sort normally:
#!/usr/bin/perl use warnings; use strict; use Test::More; use Test::Deep; my @in = -2 .. 2; my @exp = (0, 1, 2, -2, -1); my @sorted = sort { ((-1, 0, 1)[$a <=> 0] <=> (-1, 0, 1)[$b <=> 0]) || ($a <=> $b) } @in; cmp_deeply([@sorted], [@exp]); done_testing();

Update: It seems comparable to grepfirst, thus slower than sortfirst.

Update 2: This seems to be a bit faster than grepfirst, but still not as fast as sortfirst:

((($a <=> 0) & 3) <=> (($b <=> 0) & 3)) || ($a <=> $b)

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

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