Or just keep the previous value in a variable. I'd understand "sorting by values" as walking the hash keys in the order of the values. 
#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

my %color_of = (
    apple   => 'red',
    orange  => 'orange',
    grape   => 'purple',
    tomato  => 'red',
    lettuce => 'green',
    peanut  => 'tan',
);

my $previous;
for my $fruit_or_vegetable (
    sort { $color_of{$a} cmp $color_of{$b} } keys %color_of
) {
    say "$previous before $fruit_or_vegetable" if defined $previous;
    $previous = $fruit_or_vegetable;
}

[download]
($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Re: Look at the next value of hash when sorting by values by choroba
in thread Look at the next value of hash when sorting by values by Cow1337killr

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