Joseph Paish 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
>
> 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?
>
if the file is already sorted, using a hash will do the trick:
#!/usr/bin/perl -w
use strict;
my %hash;
open(DATA,"sorted_file.txt") || die $!;
$hash{(split)[1]} = $_ while(<DATA>);
close(DATA);
print for(values %hash);
__END__
prints:
02/05/03 ghi.th 987 2345 94
02/01/03 def 987 3453 456
01/05/03 abc 876 2356 87
01/09/03 ank 875 234 98098
the disadvantage is that the output is bit out of order.
david
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