Re: Lookup closest hash key

Nah, the whole point of a hash is that it obviates coding the B-tree yourself


my %distances = (
    452 => 'London',
    678 => 'Paris',
    890 => 'Rome',
);

print nearest( 672, \%distances ) . "\n";

sub nearest{
    my ( $dist, $href ) = @_;
    my ( $answer ) = ( sort { abs( $a - $dist ) <=> abs( $b - $dist ) 
+} keys %$href );
    return $href -> { $answer };
}
[download]

update: you could use the orcish manoeuvre to minimise sort iterations but something as simple as abs( x - y ) seems too cheap to be worth it.

One world, one people

Comment on Re: Lookup closest hash key Download Code

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Re^2: Lookup closest hash key by Anonymous Monk on Oct 08, 2014 at 19:08 UTC
Didn't you mean this, rather? `sub nearest{ my ( $dist, $href ) = @_; my ( $answer ) = ( sort { abs( $a - $dist ) <=> abs( $b - $dist ) +} keys %$href )[0]; return $href -> { $answer }; }` [download] Otherwise this is a great trick, thanks!	[reply] [d/l]
Re^3: Lookup closest hash key by choroba (Cardinal) on Oct 09, 2014 at 07:17 UTC
`my ($answer)` creates list context, so the `[0]` at the end is not needed: it is a list assignment, the first element on the left gets the first element on the right. With the index at the end, you can drop the parentheses on the left, as it is a scalar assignment: `my $answer = ( sort { abs( $a - $dist ) <=> abs( $b - $dist ) } keys % +$href )[0];` [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l] [select]