Retrieving a subset of XML nodes with PHP

Question

Using PHP, how do I get an entire subset of nodes from an XML document? I can retrieve something like:

Answer 1

The answer turned out to be a combination of the xpath suggestion and outputting with asXML().

Using the example given by Josh Davis:

$people = simplexml_load_string(
      
        
          
            Jane Doe
            21
          
          
            John Smith
            34
          
        '
    );

    // get all  nodes
    $nodes = $people->xpath('/people/certain');

    foreach ( $nodes as $node ) {
      $result .= $node->asXML()."\n";
    }
    echo $result;