my $myhash = \%HoH;
my $dom = 'XML::LibXML'->load_xml(location => 'test.osm');
for my $node ($dom->findnodes('/osm/node')) {
    my $tag = $node->findnodes('tag[@k="name"]')->[0];
    my $key = "$node->{lat}.$node->{lon}";
    if (exists $HoH{$key}){
      $tag->{v} = $HoH{$key}->{name};
      $node->{id} = $HoH{$key}->{id};
    }
    else {
        print "$_\n" for keys %HoH;
      my($lat_key, $lon_key) = split(/./, $, 2);
      my $new_node = 'XML::LibXML::Element'->new("node");
      my $id = 'XML::LibXML::Attr'->new("id",$HoH{$key}->{id});
      my $lat = 'XML::LibXML::Attr'->new("lat",$lat_key);
      my $lon = 'XML::LibXML::Attr'->new("lon",$lon_key);
      $new_node->setAttribute($id);
      $new_node->setAttribute($lat);
      $new_node->setAttribute($lon);
      my $new_node_child = 'XML::LibXML::Element'->new("tag");
      my $k = 'XML::LibXML::Attr'->new("k",'name');
      my $v = 'XML::LibXML::Attr'->new("v",$HoH{$key}->{name});
      $new_node_child->setAttribute($k);
      $new_node_child->setAttribute($v);
      $new_node->addChild($new_node_child);
    }

}
$dom->toFile('new_test.osm');