Re: [Geotools-gt2-users] Fun with filters ... or not

[Jim Hughes]

Hi Gaby,

If seems that you could work in this manner...
1. Build a filter for points within the bounds of the polygon shapefile.

// (Something like this may be useful.)
FilterFactory ff = CommonFactoryFinder.getFilterFactory2();
ReferencedEnvelope envelope = polygonShapefile.getBounds();
Filter boundsFilter = ff.createBBoxExpression("geomField", envelope);

2.  Iterate through the points, evaluate the boundsFilter.  Failing 
points can go into the collection for the points outside the polygon 
shapefile.

3.  For those accepted, you can evaluate the OR filter you've previously 
described.  Points which satisfy the filter are in, and those which do 
not are inside in the bounds, but outside the collection of polygons.

As another note, depending on your situation, it may be beneficial to 
read out the polygons into a GeometryCollection and simplify things with 
union/buffer(0).  This one geometry can be used to create a potentially 
more simple filter.  If the data size grows, you could extend this 
approach to use R-trees.

Cheers,

Jim

On 05/07/2015 01:24 AM, Gabriella Turek wrote:
I have two shape files, one of polygons and one of points. I want to 
find out
1) the id’s of all the points that fall into a polygon
2) the id’s of the points that do not fall in any polygon
3) the id’s of any points that lie outside the bonding box of the 
polygons file

This is how I got started:

public static Map<FeatureId, Integer> 
computeAssetsExposure(SimpleFeatureCollection assetsfc, 
SimpleFeatureCollection exposurefc) throws IOException {

Class<?> geomAsset = 
assetsfc.getSchema().getGeometryDescriptor().getType().getBinding();

Class<?> geomExposure = 
exposurefc.getSchema().getGeometryDescriptor().getType().getBinding();

String geomExposureAttr = 
exposurefc.getSchema().getGeometryDescriptor().getLocalName();

if (geomExposure.equals(Polygon.class) || 
geomExposure.equals(MultiPolygon.class))

{

CommonLogger.getInstance().logInfo(ExposureCalculator.class, 
"Unsupported configuration");

returnnull;

}

// Points that fall in a polygon

Filter orFilter = null;

try (SimpleFeatureIterator eIt = exposurefc.features()) {

booleanstart= true;

while (eIt.hasNext()) {

SimpleFeature expFeature = eIt.next();

Geometry expGeom = (Geometry) expFeature.getDefaultGeometry();

String expr = "INTERSECTS(" + geomExposureAttr + ", " + 
expGeom.toText() + ")";

if (start)

{

orFilter = CQL.toFilter(expr);

start = false;

} else {

orFilter = Filters.or(CommonFactoryFinder.getFilterFactory2(), 
orFilter, CQL.toFilter(expr));

}

}

}


SimpleFeatureCollection exposedAssets = assetsfc.subCollection(orFilter);

              ??????

      }


To get the Ids I think I could use an 
IdCollectorFilterVisitor.ID_COLLECTOR, but I can’t figure out how to 
use it.

Once I’ve found out the points that are in a polygon, is there a quick 
way to find out the id’s of the remaining ones? Or do I have to build 
Filters.and(…) with the individual filters being DISJOINT filters?

How do I find out if there are any points that lie outside the extent 
of the polygon shapefile?

Many thanx!

Gaby




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Widest out-of-the-box monitoring support with 50+ applications
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