Haversine (exp)

{{#images:version700-32x32.png|stock}} <source lang='delphi'>function haversine(geoloc:TGeolocation; lat,long:Double):Double;</source>

Retourne la distance entre l'attribut Geolocation et un jeu de coordonnées.

Exemple :

Utilisation d'arguments

<source lang="delphi"> //Procedure TestGeolocation; var sel:TSelector; S:string; stag:string; inst:WFAddress; dd:double; lat,long:double; begin

 // looks for address in 100 meters range from a point.
 //
 lat := 38.897147;
 long := -77.043934;
 sel := WFAddress.CreateSelector('haversine(geoloc,%2,%3) < %1','-haversine(geoloc,%2,%3)',true,[0.1,lat,long]);

 foreach inst in  sel.AsCursor do
  begin
    dd := inst.Geoloc.haversine(38.897147,-77.043934);
    showMessage(Format('%s %0.4f',[inst.Address1,dd]));
  end;

end; </source>

Utilisation de constantes

<source lang="delphi"> //Procedure TestGeolocation; var sel:TSelector; S:string; stag:string; inst:WFAddress; dd:double; begin

 // looks for address in 100 meters range from a point.
 //
 sel := WFAddress.CreateSelector('haversine(geoloc,38.897147,-77.043934) < %1',,true,[0.1]);

 foreach inst in  sel.AsCursor do
  begin
    dd := inst.Geoloc.haversine(38.897147,-77.043934);
    showMessage(Format('%s %0.4f',[inst.Address1,dd]));
  end;

end; </source>

Requête SQL générée par ces exemple:

select t0.* from dbo.WFADDRESS t0
where dbo.udf_haversine(t0.Geoloc_lat,t0.Geoloc_long,38.897147,-77.043934) < 1.000000000000000060E-001
order by t0.oid

Voir aussi:

{{#if:Expressions objets (code)|

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