GeoReverseQuery

circles.xqy

xquery version "1.0-ml";

(: a whole bunch of random circles to make the reverse-query harder :)
let $n := 10000

for $count in (1 to $n)
let $lat := xdmp:random(180) - 90
let $lon := xdmp:random(360) - 180
let $query-doc := 
  
  let $a := cts:point( $lat,$lon)
  let $b := cts:point( $lat + 0.0001, $lon)
  let $circle := cts:circle( cts:distance($a, $b), $a)
  return
  <query>
    {cts:element-geospatial-query( xs:QName("point"), $circle , ("coordinate-system=wgs84"))}
    <a>{$a}</a>
    <b>{$b}</b>
  </query>

return
xdmp:document-insert( fn:concat("/circle-",$count,".xml"), $query-doc );

(: the actual matching circle :)

let $query-doc := 
  
  let $a := cts:point( 10.0005,36)
  let $b := cts:point( 10.00051,36)
  let $circle := cts:circle( cts:distance($a, $b), $a)
  return
  <query>
    {cts:element-geospatial-query( xs:QName("point"), $circle , ("coordinate-system=wgs84"))}
    <a>{$a}</a>
    <b>{$b}</b>
  </query>

return
xdmp:document-insert( fn:concat("/matching-cicle.xml"), $query-doc )

reverse-query.xqy

xquery version "1.0-ml";

(: the line of points which will become a reverse query to match circles:)

let $a := cts:point( 10.0005, 36)
let $b := cts:point( 10.00052, 36)
let $distance := cts:distance($a, $b)
let $bearing := cts:bearing($a, $b)
let $steps := 100
let $step-distance := $distance div $steps
let $points := 
   for $i in (0 to $steps)
   return
   cts:destination($a, $bearing, $step-distance * $i)

let $doc :=
<document>{
  for $point in $points
  return
  <point>{$point}</point>
}</document>

return
(

cts:search( /,  cts:reverse-query( $doc ) ) ,
xdmp:elapsed-time()
)