As alternative to XML::XPath, try XML::LibXML (XML::LibXML::XPathContext).

back to your problem, try this (not tested):

my $xp = XML::XPath->new(filename=>$file);
my $nodelist = $xp->find ('//w/a');

my %map;

while (my $node = $nodelist->shift) {
  my $key = join ':',
     $node->getParentNode->getAttribute ('id'),
     $node->getAttribute ('name')
  ;

  push @{ $map{$key} }, $node;
}

for my $n (1 .. 32812) {
  my @wns = @{ $map{$n . ':' . 'wn'} || []);
  my @ls = @{ $map{$n . ':' . 'l'} || []);
}
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