Re: Lookup closest hash key

[(anonymized user)]

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 };
}

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.

[Anonymous Monk]

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 };
}

Otherwise this is a great trick, thanks!

[choroba]

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];