XQuery/DBpedia with SPARQL - Stadium locations

At the risk of being repetitious, here is another script which mashes up data from DBpedia with GoogleMaps, this time to show the location of all venues in a supplied Wikipedia Category of venues.

Examples

Football Venues in England

• kml
• GoogleMap

Football Venues in Scotland

• kml
• GoogleMap

Script

(: 
   This accepts a category of stadiums and generates a kml map of all stadiums
:)

declare namespace r = "http://www.w3.org/2005/sparql-results#";
declare variable $query := "
PREFIX p: <http://dbpedia.org/property/>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
PREFIX geo: <http://www.w3.org/2003/01/geo/wgs84_pos#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT * WHERE
  {?ground skos:subject <http://dbpedia.org/resource/Category:Football_venues_in_England>.
  ?ground geo:long ?long.
  ?ground geo:lat ?lat.
  ?ground rdfs:label ?groundname.
  OPTIONAL {?ground foaf:depiction ?image .}.
  OPTIONAL {?club p:ground ?ground.  ?club rdfs:label ?clubname . FILTER (lang(?clubname) = 'en')}.
  OPTIONAL {?ground foaf:page ?wiki.}.
  FILTER (lang(?groundname) ='en'). 
 } 
"; 

declare function local:execute-sparql($query as xs:string) {
 let $sparql := concat("http://dbpedia.org/sparql?format=xml&amp;default-graph-uri=http://dbpedia.org&amp;query=",
                encode-for-uri($query)
              )
 return doc($sparql)
};

declare function local:sparql-to-tuples($rdfxml) {
  for $result in $rdfxml//r:result
  return
   <tuple>
      { for $binding in $result/r:binding
        return        
         if ($binding/r:uri)
           then  element {$binding/@name} {
                  attribute type {"uri"} , 
                  string($binding/r:uri) 
                }
           else  element {$binding/@name} {
                  attribute type {$binding/@datatype}, 
                  string($binding/r:literal)
                }
       }
   </tuple>
 };

declare option exist:serialize "method=xhtml media-type=application/vnd.google-earth.kml+xml highlight-matches=none"; 

let $category := request:get-parameter("category","Football_venues_in_England")
let $queryx := replace($query,"Football_venues_in_England",$category)
let $result:= local:execute-sparql($queryx)
let $tuples := local:sparql-to-tuples($result)

let $x := response:set-header('Content-disposition','Content-disposition: inline;filename=stadiums.kml;')

return

<Document>
  <name>{replace($category,"_"," ")}</name> 
  <Style id="stadium">
    <IconStyle>
     <Icon><href>http://maps.google.com/mapfiles/kml/shapes/ranger_station.png</href>
    </Icon>
    </IconStyle>
  </Style>
   {
   for $groundid in distinct-values($tuples/ground)
   let $groundTuples := $tuples[ground=$groundid]
   let $ground := $groundTuples [1]
   let $name := string($ground/groundname)
   let $lat := xs:decimal($ground/lat)
   let $long := xs:decimal($ground/long)
   let $clubs := string-join($groundTuples/clubname,", ")
   let $wiki := string($ground/wiki)
   let $description := 
     <div>
     Ground of {$clubs} 
     {if ($ground/image) then (<br/>,<img src="{$ground/image}"/>) else () }
     <br/>
      <a href='{$groundid}'>DBpedia</a>
      <a href='{$wiki}'>Wikipedia</a>   
     <a href="http://images.google.co.uk/images?q=stadium+{$name}">Google Images</a>
    </div>
   return 
   <Placemark>
    <name>{$name}</name>
    <description>
    {util:serialize($description,"method=xhtml")}
     </description>
    <Point> 
    <coordinates>{concat($long, ",",$lat,",0")}</coordinates>
    </Point>
    <styleUrl>#stadium</styleUrl>
   </Placemark>
  } 
</Document>