Question

I have a program that prints out the location of commas in a paragraph of text in the form

For example if the paragraph is

one,two,three
three and a half
four,five
six
seven,eight

The program will print

0:4
0:8
2:5
4:6

I would like to use this output to create an array where the numbers after the colon are listed across columns in the row specified by the index before the colon. The array formed by the coordinates above would be

4 8
<blank or character '.'>
5
<blank or character '.'>
6

so array[0,0] = 4, array[0,1] = 8
array[1,0] = empty
array[2,0] = 5
etc…

I bet this is simple but I need help to write it.

$data_file="file.out"; 
open(DAT, $data_file) || die("Could not open file!"); 
@raw_data=<DAT>; 
close(DAT);

my %array;

my $line = 0;

foreach $newline(@raw_data) {
    chomp;

while ( $newline=~m/(,|;|:|and)/) {
            push @{ $array{$line} }, pos($newline);  # autovivification
}

    $line++; }

Answer 1

Program

#!/usr/bin/env perl

use strict;
use warnings;

my %array;

my $line = 0;
while (<DATA>) {
    chomp;

    while ( /(,|;|:|(?:and))/g ) {
        my $position = pos() - length($1) + 1;
        push @{ $array{$line} }, $position;  # autovivification
    }

    $line++;
}

for ( sort { $a <=> $b } keys %array ) {
    my $flattened_value = join ', ', @{ $array{$_} };
    print "$_ -> $flattened_value\n";
}

__DATA__
one,two,three
three and a half
four,five
six
seven,eight

Output

0 -> 4, 8
1 -> 7
2 -> 5
4 -> 6

Refer: chomp, join, keys, sort, split.

Refer the following documents to get an understanding of Perl’s data structures and especially autovivification which has been used in this example.

• perldoc perlref
• perldoc perlreftut