On Tue, 24 Apr 2007 13:33:32 +0200, Andrej Kastrin wrote:
> Question about the sum function; the file structure is as follows:
>
> A|100
> A|200
> A|150
> B|20
> B|90
> C|10
> C|30
> C|300
>
> The result I want to obtain is to sum values in the second column
> (columnB) for each particular letter in the first column (ColumnA); e.g.:
>
> A|450
> B|100
> C|330
>
> I don't want to use hash structure because the input file is very large.
> Is there any simple way to do that step-by-step: to sum up values in
> columnB until the letter in columnA changes and print the result...
If the first column is only a letter how many possible values could there
be? How could a hash get too big? You wouldn't even need a script, you
could do it in one line:
$ cat input
A|100
A|200
A|150
B|20
B|90
C|10
C|30
C|300
$ perl -F'\|' -lane '$h{$F[0]} += $F[1]; END{print "$_: $h{$_}" \
for sort keys %h}' input
A: 450
B: 110
C: 340
--
Peter Scott
http://www.perlmedic.com/
http://www.perldebugged.com/
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