User:Tagtheworld/SimpleXMLElement::xpath

SimpleXMLElement::xpath

derived from a very interesting threadː http://stackoverflow.com/questions/30316371/extracting-data-from-osm-xml-file-with-php

stackoverflow user har07 notesː

You can use SimpleXMLElement::xpath to get both "via" and the corresponding "idnode" values. For example :

$raw = <<<EOF
<root>
    <way id="28747493" visible="true" version="7" changeset="9347177" timestamp="2011-09-19T21:48:11Z" user="Camilo Alvarez" uid="492132">
      <nd ref="316077528"/>
      <nd ref="316077503"/>
      <tag k="highway" v="primary"/>
      <tag k="lanes" v="1"/>
      <tag k="name" v="Calle 51"/>
      <tag k="oneway" v="yes"/>
      <tag k="ref" v="Boyacá"/>
     </way>
    <way id="28747492" visible="true" version="9" changeset="7227086" timestamp="2011-02-08T15:33:22Z" user="dmartinh" uid="314700">
      <nd ref="358031212"/>
      <nd ref="316077505"/>
      <tag k="foot" v="permissive"/>
      <tag k="highway" v="footway"/>
      <tag k="name" v="Calle 52"/>
     </way>
</root>
EOF;
$xml = simplexml_load_string($raw);

foreach($xml->xpath("//way") AS $way){
    $via = $way->xpath("tag[@k='name']/@v")[0];
    foreach($way->nd AS $nd){
        $idnode = $nd["ref"];
        echo $idnode .", ". $via  ."<br>";
    }
}

Demo

output :

316077528, Calle 51
316077503, Calle 51
358031212, Calle 52
316077505, Calle 52

xpath explanation:

   //way selects all <way> elements anywhere in the XML document.

   tag[@k='name'] selects <tag> child of current context node having k attribute value equal name. Then from that <tag>, /@v returns v attribute.

thanks to stackoverflow user har07 - cf http://stackoverflow.com/questions/30316371/extracting-data-from-osm-xml-file-with-php