From your sample data/output it's not quite clear to me what you mean by "group on A and D"... but here's something that groups by A alone: 

#!/usr/bin/perl

my %groups;

while (<DATA>) {
    my ($grp, @other) = split ' ';

    for my $field (@other) {
        my ($name, $val) = split /:/, $field;
        
        if ($name eq "STR") {
            $groups{$grp}{$name} = $val unless defined $groups{$grp}{$
+name};  # first
        } elsif ($name eq "END") {
            $groups{$grp}{$name} = $val;    # last
        } elsif ($name eq "CNT") {
            $groups{$grp}{$name} += $val;   # sum
        } else {
            $groups{$grp}{$name}{$val}++;   # unique values
        }
    }
}

#use Data::Dumper;      # debug
#print Dumper \%groups;

for my $grp (sort keys %groups) {
    my $fields = $groups{$grp};
    
    print $grp;
    for my $name (qw(B C D)) {
        my @elems = keys %{ $fields->{$name} };
        my $val = @elems > 1 ? "MULTIPLE" : $elems[0];
        print "  $name:$val";
    }
    for my $name (qw(CNT STR END)) {
        print " $name:$fields->{$name}";
    }
    print "\n";
    
}

__DATA__
A:1  B:2  C:3 D:4  CNT:1 STR:1 END:2
A:1  B:7  C:3 D:4  CNT:1 STR:2 END:3
A:1  B:2  C:3 D:4  CNT:1 STR:3 END:4
A:2  B:2  C:3 D:5  CNT:1 STR:4 END:5
A:2  B:2  C:3 D:5  CNT:5 STR:5 END:10
A:3  B:2  C:3 D:4  CNT:1 STR:11 END:12

[download]

Output: 

A:1  B:MULTIPLE  C:3  D:4 CNT:3 STR:1 END:4
A:2  B:2  C:3  D:5 CNT:6 STR:4 END:10
A:3  B:2  C:3  D:4 CNT:1 STR:11 END:12

[download]

(STR and END are assumed to be sorted on input — in case they aren't, you'd need to compute the minimum and maximum value instead of taking the first and the last...)

In reply to Re^3: working with files by almut
in thread working with files by smanicka

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.