my %sum_of;
while (<DATA>) {
    my ($k, $v) = split /,/;
    $sum_of{$k} += $v;
}

print "$_,$sum_of{$_}\n" for sort keys %sum_of;

__DATA__
2010-02-12_aaa,654
2010-02-12_aaa,248
2010-02-12_bbb,374
2010-02-12_ccc,158
2010-02-13_aaa,745
2010-02-13_bbb,786
2010-02-13_bbb,354
2010-02-13_ddd,852
2010-02-14_bbb,754
2010-02-14_aaa,169
2010-02-14_ccc,965
2010-02-14_ccc,756
[download]

Output:

2010-02-12_aaa,902
2010-02-12_bbb,374
2010-02-12_ccc,158
2010-02-13_aaa,745
2010-02-13_bbb,1140
2010-02-13_ddd,852
2010-02-14_aaa,169
2010-02-14_bbb,754
2010-02-14_ccc,1721
[download]

I wrote the following code to test the method u gave me.

use strict;
use warnings;
my @content;
my @files;
my $dir;

my $input1 = "source/host1/";
my $input2 = "source/host2/";
my $name = "volume_2010_02";
#my $date = "2010-02-13";

opendir DIR1, "$input1";
my @files1= grep {$_ ne '.' && $_ ne '..' } readdir (DIR1);

@files = @files1;
#print @files,"\ninput file 1\n";

$dir = $input1;
#print $dir,"\ninput dir 1\n";
my @content1 = &readfiles(@files,$dir);
#print @content1,"\nFILE 1 Content\n\n";

@content =();
opendir DIR2, "$input1";
my @files2= grep {$_ ne '.' && $_ ne '..' } readdir (DIR2);

@files = @files2;
#print @files,"\ninput file 2\n";

$dir = $input2;
#print $dir,"\ninput dir 2\n";

my @content2 = &readfiles(@files,$dir);
#print @content2,"\nFILE 2 Content\n\n";
push @content1,@content2;
my @file = sort {$a cmp $b} @content1;
print @file,"\nPush output\n\n";
my %output;
my $print;
my $semiprint;
foreach(@file)
{
    #print $_,"\nCOntent1\n\n";
    my ($key,$val) = split (/\,/,$_);
    $semiprint .= "$key,$val\n";
    #print $semiprint,"\nsemi in loop\n\n";
    $output{$key} += $val;
    $print .="$key,$output{$key}\n";
    #print $print,"\nFinal output\n\n";
}
#print $print,"\nFinal output\n\n";
#print $semiprint,"\nsemi output\n\n";
open OUTPUT, "> target/1.dat";
print OUTPUT $print;

sub readfiles
{
    my @file = @files;
    my $directory = $dir;
    
    foreach(@file)
    {
        #print $_,"\nFILE NAME\n";
        if($_ =~ /^$name/)
        {
            #print $_,"\nFile found \n";
            open FILE,"< $dir/$_";
            while(<FILE>)
            {
                chomp;
                push @content,$_;
            }
            
        }
    }
    return @content;
}
[download]

Now as you can see i am reading the same data from two files(the data being same as i gave earlier) in diferrnt directories. So, my final output should have sum of values of all the similar keys in both the input files. Following are the input file and result.


__CONTENT FILE 1__
2010-02-12_aaa,654
2010-02-12_bbb,374
2010-02-12_ccc,158
2010-02-13_aaa,745
2010-02-13_bbb,786
2010-02-13_ddd,852
2010-02-14_bbb,754
2010-02-14_aaa,169
2010-02-14_ccc,965
[download]




__CONTENT FILE 2__
2010-02-12_aaa,654
2010-02-12_bbb,374
2010-02-12_ccc,158
2010-02-13_aaa,745
2010-02-13_bbb,786
2010-02-13_ddd,852
2010-02-14_bbb,754
2010-02-14_aaa,169
2010-02-14_ccc,965
[download]




__OUTPUT__
2010-02-12_aaa,654
2010-02-12_aaa,1308
2010-02-12_bbb,374
2010-02-12_bbb,748
2010-02-12_ccc,158
2010-02-12_ccc,316
2010-02-13_aaa,745
2010-02-13_aaa,1490
2010-02-13_bbb,786
2010-02-13_bbb,1572
2010-02-13_ddd,852
2010-02-13_ddd,1704
2010-02-14_aaa,169
2010-02-14_aaa,338
2010-02-14_bbb,754
2010-02-14_bbb,1508
2010-02-14_ccc,965
2010-02-14_ccc,1930
[download]




__EXPECTED OUTPUT__
2010-02-12_aaa,1308
2010-02-12_bbb,748
2010-02-12_ccc,316
2010-02-13_aaa,1490
2010-02-13_bbb,1572
2010-02-13_ddd,1704
2010-02-14_aaa,338
2010-02-14_bbb,1508
2010-02-14_ccc,1930
[download]


Can you tell me how i can omit the old data after aggregation. Or in case of non similar key just print it in the output.

Thanks
AvantA

You can't build your output string until you've processed all the entries in your files. Replace the print just before your subroutine with

print OUTPUT "$_,$output{$_}\n" for sort keys %output;
[download]

Your file will now contain:

2010-02-12_aaa,1308
2010-02-12_bbb,748
2010-02-12_ccc,316
2010-02-13_aaa,1490
2010-02-13_bbb,1572
2010-02-13_ddd,1704
2010-02-14_aaa,338
2010-02-14_bbb,1508
2010-02-14_ccc,1930
[download]

Your next task is to tidy up your source code, it's a mess :-)

Some hints:

• You use strict and warnings. This is very good.
• Always check that your opens and opendirs succeeded.
• Don't call subroutines using &readfiles(...). You don't need the "&" and it doesn't do what you think it does.
• Pick more meaningful variable names, @files and @files2 are rarely good choices.
• You don't seem to understand the point of calling subroutines with parameters. See perlsub.
• Always declare variables in the smallest possible scope. Coping with Scoping may help (its old, but still worth a read).
• Most importantly, enjoy your Perl programming.

you simply are genius man!! thanks will try it asap but i guess it will work.. thanks... :)

use Modern::Perl;
use Data::Dump qw(dump);

my %result;
for (<DATA>) {
	my ($key,$num) = split /,/;
	$result{$key} += $num;
}

say dump \%result;

__DATA__
2010-02-12_aaa,902
2010-02-12_bbb,374
2010-02-12_ccc,158
2010-02-13_aaa,745
2010-02-13_bbb,1140
2010-02-13_ddd,852
2010-02-14_bbb,754
2010-02-14_aaa,169
2010-02-14_ccc,1721

{
  "2010-02-12_aaa" => 902,
  "2010-02-12_bbb" => 374,
  "2010-02-12_ccc" => 158,
  "2010-02-13_aaa" => 745,
  "2010-02-13_bbb" => 1140,
  "2010-02-13_ddd" => 852,
  "2010-02-14_aaa" => 169,
  "2010-02-14_bbb" => 754,
  "2010-02-14_ccc" => 1721,
}