Re: Interchanging hash values (List::Util)

use strict;
use warnings;
use List::Util qw(reduce);

my $maxkey = reduce { $hash{$a} > $hash{$b} ? $a : $b } keys %hash;
my $minkey = reduce { $hash{$a} < $hash{$b} ? $a : $b } keys %hash;

@hash{$minkey,$maxkey} = @hash{$maxkey,$minkey};
[download]

Makeshifts last the longest.

Comment on Re: Interchanging hash values (List::Util) Download Code

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Re: Re: Interchanging hash values by BrowserUk (Patriarch) on Apr 21, 2003 at 04:50 UTC
Why make two passes? `D:\Perl\test>perl use strict; use warnings; my %h; @h{'a'..'j'} = 0..9; print %h, $/; my ($min,$max) = (keys %h); ($min,$max) = ( $h{$min} < $h{$_} ? $min : $_, $h{$max} > $h{$_} ? $ma +x : $_ ) for keys %h; @h{$min,$max} = @h{$max,$min}; print %h, $/; ^Z a0b1c2d3e4f5g6h7i8j9 a9b1c2d3e4f5g6h7i8j0` [download] Examine what is said, not who speaks. 1) When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong. 2) The only way of discovering the limits of the possible is to venture a little way past them into the impossible 3) Any sufficiently advanced technology is indistinguishable from magic. Arthur C. Clarke.	[reply] [d/l]
Re^3: Interchanging hash values (single pass - or not) by Aristotle (Chancellor) on Apr 21, 2003 at 11:39 UTC
Simply for the laziness of using List::Util. But if you're gonna optimize it, why check both conditions? An element can't be the maximum and the minimum at the same time. You're also pulling the list of all keys twice. `my ($min, $max) = (scalar each %h) x 2; ($min, $max) = ( $h{$_} < $h{$min} ? ($_, $max) : $h{$_} > $h{$max} ? ($min, $_) : ($min, $max) ) for keys %h;` [download] You could even go all out on each to remove the last bit of redundant work, and to reduce memory footprint. `my $min = each %h; my $max = each %h; if(defined $max) { local $_; ($min, $max) = ( $h{$_} < $h{$min} ? ($_, $max) : $h{$_} > $h{$max} ? ($min, $_) : ($min, $max) ) while defined($_ = each %h); } else { $max = $min; }` [download] That's all cool if your hash is really huge. If it's just a couple pairs, I'll prefer the lazy route any day. Makeshifts last the longest.	[reply] [d/l] [select]