creating multi-dimensional array from textfile in perl [closed] - multidimensional-array

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The file temp.txt has contents like this:
ABC 1234 56 PQR
XYZ 8672 12 RQP
How to store the temp.txt file into a two dimensional array, so that I can access them through the array index?

Answer 1

use File::Slurp;
use Data::Dumper;
my #arr = map [split], read_file("temp.txt");
print Dumper \#arr;
output
$VAR1 = [
[
'ABC',
'1234',
'56',
'PQR'
],
[
'XYZ',
'8672',
'12',
'RQP'
]
];

Answer 2

At a minimum, you could do this
my #file = load_file($filename);
sub load_file {
my $filename = shift;
open my $fh, "<", $filename or die "load_file cannot open $filename: $!";
my #file = map [ split ], <$fh>;
return #file;
}
This will read an argument file, split the content on whitespace and put it inside an array ref (one per line), then return the array with array refs. On exiting the subroutine, the file handle will be closed.
This is a somewhat clunky solution, in some ways. It loads the entire file into memory, it does not have a particularly fast lookup when you are looking for a specific value, etc. If you have a unique key in each row, you can use a hash instead of an array, to make lookup faster:
my %file = map { my ($key, #vals) = split; $key => \#vals; } <$fh>;
Note that the keys must be unique, or they will overwrite each other.
Or you can use Tie::File to only look up the values you want:
use Tie::File;
tie my #file, 'Tie::File', $filename or die "Cannot tie file: $!";
my $line = [ split ' ', $file[0] ];
Or if you have a specific delimiter on the lines of your file, and a format that complies with the CSV format, you can use Tie::File::CSV
use Tie::File::CSV;
tie my #file, 'Tie::Array::CSV', $filename, sep_char => ' '
or die "Cannot tie file: $!";
my $line = $file[0];
Note that using this module might be overkill, and might cause problems if you do not have a strict csv format. Also, Tie::File has a reputation of decreasing performance. Which solution is best depends largely on your needs and preferences.