Sure, just rearrange your data.

By building a hash which groups the rows together, your problem goes away. 

@a = (['a',1],['a',2],['b',3],['b',4]); # "db read"
my %aByGroup;

foreach(@a) {
  # you could just push $_->[1], but I'm guessing your
  # data is more complex, so I'm keeping the whole row
  push @{$aByGroup{$_->[0]}},$_;
}

my $old;
foreach my $group (sort keys %aByGroup) {
    my $total = 0;                          # init
    print "Section $group\n";

    foreach my $row(@{$aByGroup{$group}}) {
        $total += $row->[1];            # processrow block
        print "$row->[1]\n";        
    }

    print "$group: $total\n";           # finish row block
}

[download]

--
Mike

In reply to Re: Re: Re: How to loop over groups by RMGir
in thread How to loop over groups by eisenstein

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.