--- Joseph Paish <[EMAIL PROTECTED]> wrote:
> i have a data file that looks something like this :
> ( it is already sorted by date )
> 12/22/02 abc 123 456 789
> 12/23/02 def 246 812 98234
> 12/24/02 ank 987 23456 8762
> 12/27/02 abc 987 345 65434
> 01/05/03 abc 876 2356 87
> 01/09/03 ank 875 234 98098
> 02/01/03 def 987 3453 456
> 02/05/03 ghi.th 987 2345 94
> i need the final entry of each unique second field. in other words,
> in the output file, i would have :
> 01/05/03 abc 876 2356 87 << last abc entry
> 02/01/03 def 987 3453 456 << last def entry
> 01/09/03 ank 875 234 98098 << last ank entry
> 02/05/03 ghi.th 987 2345 94 << last ghi.th entry
> what i have done so far :
> sort data file by the second field
> while (not end of file) {
> read each record and store it in a temporary array
> keep reading until the second field changes
> if the second field changes {
> write the temporary array to the output file
> store the "just read" record in the temporary array
> }
> }
> this seems needlessly complicated. there has to be a better way.
> suggestions?
Don't keep the whole array. Just save each as your read it into a
holding scalar, and print it when the 2nd key isn't the same anymore.
Assuming you've already sorted by the second field:
my $prevrec = <>;
my $key = substr($prevrec,9,3);
while(<>) {
my $tmp = substr($_,9,3);
next if $key eq $tmp;
print $prevrec;
$key = $tmp;
$prevrec = $_;
}
print $prevrec; # either last of same, or only of new!
Somebody double-check me on this?
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