package com.esri.hadoop.hive;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.io.BytesWritable;
import com.esri.core.geometry.Envelope;
import com.esri.core.geometry.Point;
import com.esri.core.geometry.SpatialReference;
import com.esri.core.geometry.ogc.OGCGeometry;
@Description(
name = "ST_Centroid",
value = "_FUNC_(polygon) - returns the point that is the center of the polygon's envelope",
extended = "Example:\n"
+ " > SELECT _FUNC_(ST_GeomFromText('polygon ((0 0, 3 6, 6 0, 0 0))')) FROM src LIMIT 1; -- POINT(3 3)\n"
+ " > SELECT _FUNC_(ST_GeomFromText('polygon ((0 0, 0 8, 8 0, 0 0))')) FROM src LIMIT 1; -- POINT(4 4)\n"
)
public class ST_Centroid extends ST_GeometryAccessor {
static final Log LOG = LogFactory.getLog(ST_PointN.class.getName());
public BytesWritable evaluate(BytesWritable geomref) {
if (geomref == null || geomref.getLength() == 0) {
LogUtils.Log_ArgumentsNull(LOG);
return null;
}
OGCGeometry ogcGeometry = GeometryUtils.geometryFromEsriShape(geomref);
if (ogcGeometry == null){
LogUtils.Log_ArgumentsNull(LOG);
return null;
}
GeometryUtils.OGCType ogcType = GeometryUtils.getType(geomref);
switch(ogcType) {
case ST_MULTIPOLYGON:
case ST_POLYGON:
int wkid = GeometryUtils.getWKID(geomref);
SpatialReference spatialReference = null;
if (wkid != GeometryUtils.WKID_UNKNOWN) {
spatialReference = SpatialReference.create(wkid);
}
Envelope envBound = new Envelope();
ogcGeometry.getEsriGeometry().queryEnvelope(envBound);
Point centroid = new Point((envBound.getXMin() + envBound.getXMax()) / 2.,
(envBound.getYMin() + envBound.getYMax()) / 2.);
return GeometryUtils.geometryToEsriShapeBytesWritable(OGCGeometry.createFromEsriGeometry(centroid,
spatialReference));
default:
LogUtils.Log_InvalidType(LOG, GeometryUtils.OGCType.ST_POLYGON, ogcType);
return null;
}
}
}