XQuery Choropleth

event.xml

<?xml version="1.0" encoding="UTF-8"?>
<event>
  <name>Bethesda</name>
  <point>38.9846520, -77.0947092</point>
</event>

markers.xqy

(:  Make sure to specify coordinates in CCW order so that KML lighting works correctly :)
declare function local:coord-from-box($box as cts:box, $alt as xs:double){
    <kml:coordinates>
    {
        let $south := xs:string(cts:box-south($box))
        let $west := xs:string(cts:box-west($box))
        let $north := xs:string(cts:box-north($box))
        let $east := xs:string(cts:box-east($box))
        let $alt := xs:string($alt)
        return
        (
        
            fn:string-join((
                fn:string-join(($east,$south,$alt),","),
                fn:string-join(($east,$north,$alt),","),
                fn:string-join(($west,$north,$alt),","),
                fn:string-join(($west,$south,$alt),","),
                fn:string-join(($east,$south,$alt),",")
            )," ")
        )  
    }
    </kml:coordinates>
};


let $stylemap := map:map()
let $markers := 
    for $box at $x in $boxes
        let $s := xs:float($box/@s)
        let $w := xs:float($box/@w)
        let $n := xs:float($box/@n)
        let $e := xs:float($box/@e)
        let $freq := xs:integer($box/@count)
        return
      
          let $_ := if($freq eq $maxfreq) then xdmp:set($maxregion, $box) else ()
          let $alpha := if ($freq ge 1) then 0.5 else 0.1
          let $freq-prec := xs:double(fn:substring( xs:string($freq div $maxfreq), 1 , 5))
          let $color-prec := xs:double(fn:substring( xs:string((if($freq eq 0) then 1 else $freq) div $maxfreq), 1 , 5))
          let $style-name := fn:concat("s",fn:replace(xs:string($freq-prec),"\.",""))
          let $_ := if(map:get($stylemap,$style-name)) then () else map:put($stylemap, $style-name,
              <Style id="{$style-name}" xmlns="http://www.opengis.net/kml/2.2">
                  <PolyStyle>
                      <color>{local:html-color-from-percentage($color-prec, $alpha)}</color>
                      <colorMode>normal</colorMode>
                  </PolyStyle>
              </Style>
              )
          let $alt := (200000 + (800000 * $freq-prec)) * (xs:float($sidedist) div xs:float(9.0)) 
          let $ctsbox := cts:box($s,$w,$n,$e)
          return
              <Placemark  xmlns="http://www.opengis.net/kml/2.2">
                  <description>
                      <h3>{$freq} document{if($freq gt 1) then 's' else ()} in this region.</h3>
                  </description>
                  <styleUrl>#{$style-name}</styleUrl>
                  <Polygon xmlns="http://www.opengis.net/kml/2.2">
                      <extrude>1</extrude>
                      <altitudeMode>relativeToGround</altitudeMode>
                      <outerBoundaryIs>
                        <LinearRing>
                        {local:coord-from-box($ctsbox,$alt)}
                        </LinearRing>
                      </outerBoundaryIs>
                    </Polygon>
              </Placemark>

outofrange.xqy

let $boxes := 
    for $box in $searchres//search:box
    let $s := xs:float($box/@s)
    let $w := xs:float($box/@w)
    let $n := xs:float($box/@n)
    let $e := xs:float($box/@e)
    return
    if( ($s ge $lat1) and 
        ($n le $lat2) and 
        ($w ge $lon1) and 
        ($e le $lon2) ) then  
            let $_ := xdmp:set( $maxfreq,  fn:max( ($maxfreq, xs:integer( $box/@count )) ) )
            return
            $box
        else
          (: remove this box, because it is accounting for hits outside the search area :)
            ()

output.xqy

  return (
      xdmp:set-response-content-type("application/vnd.google-earth.kml+xml"),
      '<?xml version="1.0" encoding="UTF-8"?>',
      
      <kml xmlns="http://www.opengis.net/kml/2.2">
        <Document>
            <name>KML Heatmap Global</name>
            <open>1</open>
            
            {$camera}
            
            {
                <Style id="ml">
                  <IconStyle>
                    <color>FF3122D9</color>
                  </IconStyle>
                </Style>,
            
                for $key in map:keys($stylemap)
                return
                map:get($stylemap,$key),
            
                $markers
            }
        </Document>
      </kml>
      )

placemark.xml

<Placemark>
  <description>
    <h3>4 documents in this region.</h3>
  </description>
  <styleUrl>#s0012</styleUrl>
  <Polygon>
    <extrude>1</extrude>
    <altitudeMode>relativeToGround</altitudeMode>
    <outerBoundaryIs>
      <LinearRing>
        <coordinates>-54,-36,209600 -54,-27,209600 -63,-27,209600 -63,-36,209600 -54,-36,209600</coordinates>
      </LinearRing>
    </outerBoundaryIs>
  </Polygon>
</Placemark>

rewrite.xqy

xquery version "1.0-ml" ;
(: just send everything to the KML generating script :)
"/map.xqy"

search.xqy

  let $searchres := 
      search:search(
          "",
      <options xmlns="http://marklogic.com/appservices/search">
        <additional-query>
          {cts:collection-query("event")}
        </additional-query>
        <constraint name="mygeo">
        <geo-elem>
            <heatmap s="{$lat1}" w="{$lon1}" n="{$lat2}" e="{$lon2}" latdivs="{$county}" londivs="{$countx}"/>
            <facet-option>gridded</facet-option> 
            <element ns="" name="point"/> 
        </geo-elem>
        </constraint>
        
        <return-results>false</return-results>  
        <return-facets>true</return-facets>
      </options>
      )

square.xqy

  (: attempt to make the buckets square :)
  let $distx := ($lon2 - $lon1)  (: cts:distance( cts:point($lat1,$lon1), cts:point($lat1, $lon2) ) :)
  let $disty := ($lat2 - $lat1) (: cts:distance( cts:point($lat1,$lon1), cts:point($lat2, $lon1) ) :)
  let $mindist := fn:min(($distx,$disty))
  let $sidedist := $mindist div $count
  let $_ := xdmp:log(text{"sidedist",$sidedist},"error")
  let $countx := 
    if( fn:ceiling($distx div $sidedist) castable as xs:integer ) then
      xs:integer(fn:ceiling($distx div $sidedist))
    else
      $count * 2
  let $county :=
    if( fn:ceiling($disty div $sidedist) castable as xs:integer ) then
      xs:integer(fn:ceiling($disty div $sidedist))
    else
      $count

variables.xqy

(: variables that will track maximum values :)
let $maxfreq := 0
let $maxregion := ()

(: analytics bounds -- set to entire world :)
let $lat1 :=  -90
let $lat2 :=  90
let $lon1 :=  -180
let $lon2 :=  180
let $count := 80