Read from csv file and write output to a file - perl

Question

I am new to Perl and would like your help on following scenario, can you please help on this subject.
I have a CSV files with following information and I am trying to prepare a key-value pair from CSV file. Can you please help me with below scenario.
Line 1: List,ID
Line 2: 1,2,3
Line 3: 4,5,6
Line 4: List,Name
Line 5: Tom, Peter, Joe
Line 6: Jim, Harry, Tim
I need to format the above CSV file to get an output in a new file like below:
Line 1: ID:1,2,3 4,5,6
Line 2: Name:Tom,Peter,Joe Jim, Harry, Tim
Can you please direct me on how I can use Perl functions for this scenario.

Answer 1

You're in luck, this is extremely easy in Perl.
There's a great library called Text::CSV which is available on CPAN, docs are here: https://metacpan.org/pod/Text::CSV
The synopsis at the top of the page gives a really good example which should let you do what you want with minor modifications.

Answer 2

I don't think the issue here is the CSV format so much as the fact that you have different lists broken up with header lines. I haven't tried this code yet, but I think you want something like the following:
while (<>) { # Loop over stdin one line at a time
chomp; # Strip off trailing newline
my ($listToken, $listName) = split(',');
next unless $listToken; # Skip over blank lines
if ($listToken =~ /^List/) { # This is a header row
print "\n$listName: "; # End previous list, start new one
} else { # The current list continues
print "$_ "; # Append the entire row to the output
}
}
print "\n"; # Terminate the last line
Note that this file format is a little dubious, as there is no way to have a data row where the first value is the literal "List". However, I'm assuming that either you have no choice in file format or you know that List is not a legal value.
(Note - I fixed a mistake where I used $rest as a variable; that was caused by my renaming them as I went along and missing one)