challenge-110/dave-jacoby/perl/ch-2.pl


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#!/usr/bin/env perl

use strict;
use warnings;
use feature qw{ postderef say signatures state };
no warnings qw{ experimental };

use Carp;
use JSON;
use Text::CSV qw( csv );

my $json = JSON->new;
my $file = 'input.csv';

my $obj = read_csv($file);
my $jbo = transpose_csv($obj);
write_csv( $file, $jbo );

sub read_csv($file) {
    croak unless -f $file;
    my $object = csv( in => $file );
    return $object;
}

sub transpose_csv($object) {
    my $output = [];
    for my $i ( 0 .. -1 + scalar $object->@* ) {
        for my $j ( 0 .. -1 + scalar $object->[$i]->@* ) {
            $output->[$j][$i] = $object->[$i][$j];
        }
    }
    return $output;
}

sub write_csv ( $file, $csv ) {
    csv( in => $csv, out => $file );
}