How to print to specific column in a CSV from perl script

Question

I have a CSV file in the following format:

Config,name,sub,produce,negative,positive,dying
RDF-12,jakl,xol,12,4,2,4

In my perl script, I have following variables:

$config = 'LSF-13'
$produce = 34;
$positive = 6;
$dying = 3;

I am missing variables for the columns 'name', 'sub', and 'negative' but still want to place(append) my variables in their respective columns.

$file = "/lsd/filepath/text.csv";
open $fh, '>>', $file or warn "can't open";
print $fh $config, $produce, $positive, $dying;

My code is not allowing me to specify the columns I want to match with my variable however.

Desired Output:

Config,name,sub,produce,negative,positive,dying
RDF-12,jakl,xol,12,4,2,4
LSF-13,,,34,,6,3

Can you just add blank values using undef for the fields that are missing? $config, undef, undef, $produce, undef, $positive, $dying — Hambone
– Hambone, Commented Oct 16, 2018 at 18:48
What is your desired output? (How does LSF-13 get "appended" to the Config field ... like RDF-12 LSF-13 ...? — zdim
– zdim, Commented Oct 16, 2018 at 18:50
Well say $fh $config, ',', ',', $produce ... (etc). But, isn't there more to it? What if you have more lines to add, how do you designate variables (hash with column names?) — zdim
– zdim, Commented Oct 16, 2018 at 19:00

Grinnz · Accepted Answer · 2018-10-16 19:12:49Z

2

Using Text::CSV:

use strict;
use warnings;
use utf8;
use Text::CSV;

my %row = (
  Config => 'LSF-13', # keys must match the case of the columns in your CSV exactly
  produce => 34,
  positive => 6,
  dying => 3,
);
my $file = "/lsd/filepath/text.csv";

# open to read the existing column names from the first line
open my $readfh, '<:encoding(UTF-8)', $file or die "can't open $file: $!";
my $csv = Text::CSV->new({eol => $/, binary => 1, auto_diag => 2});
$csv->column_names($csv->getline($readfh));
close $readfh;

# open to append a new line
open my $writefh, '>>:encoding(UTF-8)', $file or die "can't open $file: $!";
$csv->print_hr($writefh, \%row);

edited Oct 16, 2018 at 19:12

answered Oct 16, 2018 at 19:00

Grinnz

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