Question

I have a space delimited text file I am reading and am trying to add up data based on month, the data looks like this:

Mon Apr 04 08:00:00 MDT 2011    120.72  0.3     0.707   25.609  25.609

Mon Apr 04 07:45:00 MDT 2011    119.94  0.3     0.707   25.443  25.443

I’m trying to just add up monthly totals:

#!/usr/bin/perl 

use strict;
use warnings;
use diagnostics;
use vars;

my $line;
my @data;
my @months;

my ($day, $month, $date, $time, $gmt, $year, $volt, $amp, $pf, $watt, $voltamp, 
    $voltsum, $wattsum, $count, $months, $monthlytotal );

$voltsum = 0;
$wattsum = 0;

open(DATAFILE, "@ARGV") ||  die $!;

@months = qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec );

            while (<DATAFILE>) {
            $line = $_;
            chomp $line;
            @data = split(/\s/,$line);
            $day = $data[0];
            $month = $data[1];
            $date = $data[2];
            $time = $data[3];
            $gmt = $data[4];
            $year = $data[5];
            $volt = $data[6];
            $amp = $data[7];
            $pf = $data[8];
            $watt = $data[9];
            $voltamp = $data[10];

I want to match the month, add my data up, and print the result once, but my flow control is wrong, any idea on how to do this correctly?

I want read each line, test which month it is, add all similar months together, and return the result.

    foreach $months(@months) { 
       if ( $months =~ $month  ) {
                  $voltsum += $voltamp;
                  $wattsum += $watt;
            print "$month $year $wattsum $voltsum\n";
    }
            elsif ( $months !~ $month ) {
            $voltsum = 0;
            $wattsum = 0;

}
}

}
close (DATAFILE);



#               print "Month  Year Watts     Vars\n" ;
#               print "--------------------------\n";
#               print " $months $month    $year $wattsum $voltsum\n\n";

Answer 1

You might benefit from using a module to parse your timestamp. However, a simple fix might be to do something like this:

my %sum;
while (<>) {  # instead of open on @ARGV, just use diamond operator
    my ($day, $month, $date, $time, $gmt, $year, $volt, $amp, 
        $pf, $watt, $voltamp) = split;
    $sum{"$year$month"}{'voltamp'} += $voltamp;
    $sum{"$year$month"}{'watt'} += $watt;
    ....
}

Not exactly waterproof, but it might suit your needs. Then you can simply extract the month data with

for my $month (keys %sum) {
    print "voltamp sum ($month): $sum{$month}{'voltamp'}\n";
    ....
}