Transpose rows into columns using Perl

I am newbie with Perl. I have an assignment to transpose rows into columns of a huge data.

customers         goods     transportation
----------        -----     --------------
A, B, C, D        rice      truck
E, G, D           corn      train
.............     .....     .........
T, H, K, M, N     wheat     air cargo

And I would like to have an output look like:

customers         goods     transportation
----------        -----     --------------开发者_Go百科
A                 rice      truck
B                 rice      truck
C                 rice      truck
D                 rice      truck
.............     .....     .........
N                 wheat     air cargo

Could anyone help. Thank you very much.

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Most probably you have come across the map function, study how it works and how you construct rows or columns and you will get it, good luck! :)

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Thank you all. After few hours trying I could figure out how to do my assignment. It needs some simple steps of manually intervention for the input and output, i.e. add an , at the end of the first column of the input and remove \ in the second column of the output using Excel. It is time to submit the output. I appreciate if someone has a better Perl code to solve it.

#!/usr/bin/perl
my @records;
while (<DATA>) {
    chomp;
    my @columns = split ", ", $_;
    push @records, \@columns;
}

foreach my $record (@records) {
    foreach my $column (@{$record}) {
        if (\$column != \$$record[-1]) {
            print "$column\t \\$$record[-1]\n";
        }
    }
}

__DATA__
A, B, C, D,     Rice    Truck
E, G, D,    Corn    Train
T, H, K, M, N,  Wheat   Air cargo

__OUTPUT__
A    \  Rice    Truck
B    \  Rice    Truck
C    \  Rice    Truck
D    \  Rice    Truck
E    \  Corn    Train
G    \  Corn    Train
D    \  Corn    Train
T    \  Wheat   Air cargo
H    \  Wheat   Air cargo
K    \  Wheat   Air cargo
M    \  Wheat   Air cargo
N    \  Wheat   Air cargo

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It's a long time since I looked at perl, but is this perl mod any good?

Data::Pivot