I am writing MAP REDUCE in PERL SCRIPT. I have written a MAP that outputs Key Value pair and I am writung a REDUCE to work on that Key Value Pair. The MAP command output is fed to the REDUCER and I am trying to create a hash of Key Value pair in reducer. But the hash is empty when I feed the data to it. The MAP is giving a proper output. I am facing a problem while creating the hash. Also I need to add the values of hash key that are same. How do I do that 


MAP

#!/usr/bin/perl

open (MYFILE, "$ARGV[0]")or die $!;
while ( <MYFILE> ) {

chomp;
(my $txnid,my $date,my $custid,my $amount, my $productc, my $subc, my 
+$city, my $state, my $mode) = split(",");
my $key_to_reduce = join ".", "$subc", "$state";

print "$key_to_reduce\t$amount \n";

}
close(MYFILE);

REDUCE

#!/usr/bin/perl

my %worth = ();

while (<>) {
chomp;
(my $combined, my $value) = split ("\t");
print "Key to Reducer is:$combined \n";
print "Value of the key:$value \n";
$worth{$combined} = $value;
}
print "The hash is: %worth";
foreach my $key ( keys %worth ) {
print "key: $combined, value: $worth{$combined}\n";
}

REDUCE OUTPUT

Key to Reducer is:Fencing.Missouri
Value of the key:169.68
Key to Reducer is:Cheerleading.California
Value of the key:078.61
Key to Reducer is:Field Hockey.Texas
Value of the key:085.64
Key to Reducer is:Weightlifting Belts.Florida
Value of the key:030.48

............

key: , value:
key: , value:
key: , value:
key: , value:
key: , value:
key: , value:
key: , value:
key: , value:
key: , value:

MAP OUTPUT

notroot@ubuntu:~/lab/programs$ perl transaction_map.pl /home/notroot/l
+ab/data/txns | more
Cardio Machine Accessories.Tennessee    040.33
Weightlifting Gloves.California 198.44
Weightlifting Machine Accessories.California    005.58
Gymnastics Rings.Wisconsin      198.19
Field Hockey.Tennessee  098.81

DATA

00000000,06-26-2011,4007024,040.33,Exercise & Fitness,Cardio Machine A
+ccessories,Clarksville,Tennessee,credit
00000001,05-26-2011,4006742,198.44,Exercise & Fitness,Weightlifting Gl
+oves,Long Beach,California,credit
00000002,06-01-2011,4009775,005.58,Exercise & Fitness,Weightlifting Ma
+chine Accessories,Anaheim,California,credit
00000003,06-05-2011,4002199,198.19,Gymnastics,Gymnastics Rings,Milwauk
+ee,Wisconsin,credit
00000004,12-17-2011,4002613,098.81,Team Sports,Field Hockey,Nashville 
+ ,Tennessee,credit
00000005,02-14-2011,4007591,193.63,Outdoor Recreation,Camping & Backpa
+cking & Hiking,Chicago,Illinois,credit
00000006,10-28-2011,4002190,027.89,Puzzles,Jigsaw Puzzles,Charleston,S
+outh Carolina,credit
00000007,07-14-2011,4002964,096.01,Outdoor Play Equipment,Sandboxes,Co
+lumbus,Ohio,credit
00000008,01-17-2011,4007361,010.44,Winter Sports,Snowmobiling,Des Moin
+es,Iowa,credit

COMMAND

perl transaction_map.pl /home/notroot/lab/data/txns | perl transaction
+_reduce.pl

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In reply to Create a Hash Dynamically and add the values of same key by rahulruns

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