How to Deallocate All References Elements from an Array

How to delete a specific array in an array of array references?

Code such as

if (@array_1 == @array_2)   # same number of elements?

tests whether the arrays have the same number of elements. This is because the == operator imposes the scalar context on both sides, and in scalar context an array is evaluated to return the number of its elements.

To test whether arrays are equal you need to compare their elements, with a few additional checks and refinements. As for many things in Perl, there are also modules that do that for us.

With Array::Compare for example, in its simplest usage:

use Array::Compare;

my $comp = Array::Compare->new;    
...
if ($comp->compare(\@ary1, \@ary2))  # they are equal

There is more that can be set up with the module, and there is a number of other modules for all kind of work with arrays and lists.

The code in the question also uses = (assignment!) instead of comparison ==.

With a few simplifications

use warnings;
use strict;
use Data::Dump qw(dd);  # to show complex data structures

use Array::Compare;

my $cobj = Array::Compare->new;

my @data = ( 
   ['CTCTTGCCTCAATCATATAT', 'CTCTTGCCTCATTGATATAT', ... ],
   ['CACTTGCCTCAATGTAATAT', 'TATCATTGCCCAATTTAAGT', ... ],
   ...
);

my @ary_to_del = ('CACTTGCCTCAATGTAATAT', 'TATCATTGCCCAATTTAAGT', ...);

foreach my $ra (@data) {
    @$ra = () if $cobj->compare(\@ary_to_del, $ra);
}

dd \@data;

This "empties" the anonymous arrays in @data that are equal to @ary_to_del, as code in the question does, but their array references remain in @data even as there is nothing in them.

If you were rather to remove such elements altogether then overwrite the array

@data = grep { not $cobj->compare(\@ary_to_del, $_) } @data;

instead of the foreach loop above. This uses grep to filter the input list, whereby only elements for which the code block evaluates true are returned in the output list, assigned to @data.

Remove all elements contained in another array

Use the Array.filter() method:

myArray = myArray.filter( function( el ) {
  return toRemove.indexOf( el ) < 0;
} );

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Small improvement, as browser support for Array.includes() has increased:

myArray = myArray.filter( function( el ) {
  return !toRemove.includes( el );
} );

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Next adaptation using arrow functions:

myArray = myArray.filter( ( el ) => !toRemove.includes( el ) );

remove object from array with just the object's reference

Simply use Array.prototype.indexOf:

let index = MyArray.indexOf(TheObject);
if(index !== -1) {
  MyArray.splice(index, 1);
}

Keep in mind that if targeting IE < 9 you will need to introduce a polyfill for indexOf; you can find one in the MDN page.

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