sub replace {
    my ($line, $nodes, $suffix) = @_;
    (my $matchNodes = $nodes) =~ s/,/|/g;
    $line =~ s/\b($matchNodes):./$1:$suffix/g;
    return $line;
}

$line = replace($line, $runset{'POWER-NODE'}, 'P');
$line = replace($line, $runset{'GROUND-NODE'}, 'G');