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Re: Numeric Sorting on Characters

by johngg (Abbot)
on Aug 14, 2013 at 21:31 UTC ( #1049484=note: print w/ replies, xml ) Need Help??


in reply to Numeric Sorting on Characters

Another way is to use a Schwartzian Transform passing the key, an indicator whether the cpu is "-" (1 - TRUE or 0 - FALSE) and the cpu value in an array ref. Sorting can then be done on the indicator first then on cpu value but the second sort term is a ternary so that comparing two items with a "-" cpu value immediately returns zero.

$ perl -Mstrict -Mwarnings -E ' my $passes = { t1 => { cpu => 73, xx => 3 }, t2 => { cpu => q{-}, xx => 7 }, t3 => { cpu => 17, xx => 0 }, t4 => { cpu => 49, xx => 6 }, t5 => { cpu => q{-}, xx => 4 }, t6 => { cpu => 11, xx => 5 }, }; say for map { $_->[ 0 ] } sort { $a->[ 1 ] <=> $b->[ 1 ] || ( $a->[ 1 ] ? 0 : $a->[ 2 ] <=> $b->[ 2 ] ) } map { [ $_, $passes->{ $_ }->{ cpu } eq q{-}, $passes->{ $_ }->{ cpu }, ] } keys %$passes;' t6 t3 t4 t1 t2 t5 $

I hope this is of interest.

Update: Ignore this, it doesn't seem to be sorting correctly :-(

Update 2: I was bitten on the bum by a silly precedence problem that should have occurred to me sooner. Replacing

sort { $a->[ 1 ] <=> $b->[ 1 ] || $a->[ 1 ] ? 0 : $a->[ 2 ] <=> $b->[ 2 ] }

with

sort { $a->[ 1 ] <=> $b->[ 1 ] || ( $a->[ 1 ] ? 0 : $a->[ 2 ] <=> $b->[ 2 ] ) }

solved the problem.

Cheers,

JohnGG


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