MultiDimensional array Input to Single array in Perl

user_1864185 0
Viewed 58

I've the below Input and the expected output.

Input : [undef,[0,1],2]
Expected Output : [0,1,2]

Code I've written:

use Data::Dumper;
my $input=[undef,[0,1],2];
my @arr=@{$input};
@arr = grep {defined} @arr;
my @arrnew;
foreach my $value (@arr){
  if (ref $value    eq 'ARRAY') {
    push @arrnew,@{$value};
  } else {
    push @arrnew,$value;
  }
}
print Dumper(@arrnew);

Question: Although, this gives me the correct output, would like to know if any simpler way of doing this in perl.

multidimensional-array perl
2 Answers

You can roll it all into a single expression using map and grep.

use strict;
use warnings;

my $foo = [undef,[0,1],2];
my @bar = map { ref eq 'ARRAY' ? @$_ : $_ } grep defined, @$foo;

The map acts like your foreach loop and produces a new list on the way out, which gets assigned to a new array @bar. The grep you had already used, but I've changed it to use expression syntax rather than block syntax.

Note this only works for one level of depths.

user_13314510

For deeper structures, you can use a recursive subroutine:

#!/usr/bin/perl
use warnings;
use strict;

sub flatten {
    my ($thing) = @_;
    return unless defined $thing;
    return $thing unless ref $thing;
    return map flatten($_), @$thing;
}

my $input = [undef, [0, 1], 2, [[[3]]]];
my $output = [flatten($input)];

use Test::More tests => 1;
is_deeply $output, [0, 1, 2, 3];
user_10306750
Related