Paul And Joann Van Dalen wrote:
>
> Hi all,
>
> Given an input file that has the following records:
>
> 123 ABC XX112 YYYY Zzzzzzzzzz
> 123 DEF XX113 WWWW Zzzzzzzzz
> 123 EEF XX112 YYYY Zzzzzzzzzz
> 444 ccc vvbfd QQQQ ccccccccc
> 444 CCd vvbfd QQQQ ccccccccc
> 444 ddd ssddd QQQQ xxxxxxxx
>
> I need to focus on the first column (the input file is already sorted on
> that field) and, grouped by the first column, pull out
> the first record of that group.
> e.g., I would need to have the following from the above as output:
>
> 123 ABC XX112 YYYY Zzzzzzzzzz
> 444 ccc vvbfd QQQQ ccccccccc
>
> I believe I'd need something like a hash, where for every record within
> a group defined by the common value of the first column, I take the
> numerically first occurance of that group, but I don't know how to do
> that in Perl. Would it take a loop for each group within the loop for
> the entire file??
You don't need a hash but you do need some way to signal a new group.
my $prev = '';
while ( <FILE> ) {
my ( $group ) = split;
next if $group eq $prev;
# do something with the first
# line of the new group
$prev = $group;
}
John
--
use Perl;
program
fulfillment
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