MultiDimensional array Input to Single array in Perl-CodePudding

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.

CodePudding user response：

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.

CodePudding user response：

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];