my %hash = (one => 1, two => 1, three => 1);
my @keep = qw( two three );

my %keep = map { $_ => 1 } @keep;
$hash{$_} = 0 for grep !$keep{$_}, keys %hash;

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In reply to Re: performing operation on elements not in list? by ikegami
in thread performing operation on elements not in list? by Anonymous Monk

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