Rather than doing all the substr's, couldn't you just do 
$in = s/^\((.*)\)$/$1/;
my @splat = split(/,/, $in);
my ( $depth, $left );
while ( my $c = shift @splat ) {
     $left .= ( $left ? ',' : '' ) . $c;
     ++$depth if index($c, '(') >= $[;
     --$depth if index($c, ')') >= $[;
     last if $depth == 0;
}
my $right = join(',', @splat);

[download]
and then recurse on $left and $right? (Maybe searching each time for the parentheses is as hard as substr'ing, though.)

UPDATE: Per BrowserUK's response, the answer seems to be “Yes, but why?” I always thought that substr's were very expensive, but apparently not. Hurrah for premature optimisation!

In reply to Re^2: Parsing newick trees by JadeNB
in thread Parsing newick trees by citromatik

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.