Re: [Geotools-gt2-users] filter points within polygon

[Hari S. K. <ha...@la...>]

This works perfectly!  I knew there had to be a simple way to solve this 
problem, and your explanation helps me to understand things better.  Since 
there doesn't appear to be an example of this functionality in the code 
snippets I hope this post can help people in the future to be able to use 
this simple but essential functionality.
Thank you,
Hari

At 09:59 AM 12/2/2006, Andrea Aime wrote:
>Hari S. Khalsa ha scritto:
>>Does anyone know whether it is possible to read in only the features from 
>>a point shapefile that are contained within a specific geometry?
>>I'm trying to read in business locations from a point shapefile that are 
>>contained within a polygon using a Geometry filter.  I've successfully 
>>used the bounding Box filter and so I could use this to get all of the 
>>points within the envelope of a polygon.  Then I could traverse through 
>>these points and get just the ones that are in the polygon.  I'd rather 
>>not go through this extra processing though. I'm including the (rough) 
>>code that I've tried to use but with no success.  If it is possible to do 
>>what I'm trying, can someone point me at an example or guide me how to 
>>modify my code below.
>>Thanks,
>>Hari
>>   *public* FeatureCollection getBusinesses(Geometry businessArea, String 
>> businessDataset)
>>   {
>>     *try* {
>>       File businessFile = *new* File(businessDataset);
>>   URL businessURL = businessFile.toURL();
>>
>>   //get feature results
>>   ShapefileDataStore store = *new* ShapefileDataStore(businessURL);
>>   //feature type name is defaulted to the name of shapefile (without 
>> extension
>>   String name = store.getTypeNames()[0];
>>   FeatureSource source = store.getFeatureSource(name);
>>
>>   //source.getBounds().intersects((Envelope)businessArea.getEnvelope());
>>
>>   FeatureCollection currentFeatures;
>>   FilterFactory filterFactory = FilterFactoryFinder./createFilterFactory/();
>>
>>   //GeometryFilter businessAreaFilter = 
>> filterFactory.createGeometryFilter(FilterType.GEOMETRY_BBOX);
>>   //GeometryFilter businessAreaFilter = 
>> filterFactory.createGeometryFilter(FilterType.GEOMETRY_CONTAINS);
>>   //GeometryFilter businessAreaFilter = 
>> filterFactory.createGeometryFilter(FilterType.GEOMETRY_WITHIN);
>>   GeometryFilter businessAreaFilter = 
>> filterFactory.createGeometryFilter(AbstractFilter. /GEOMETRY_WITHIN/ );
>>
>>   //businessAreaFilter.addRightGeometry(filterFactory.
>>   // createBBoxExpression(overLappingEnvelope));
>>
>>
>>businessAreaFilter.addRightGeometry(filterFactory.createAttributeExpression(businessArea.toString()));
>
>Here lies the error, you want to compare against a constant, a literal, 
>not an attribute of the features you're loading.
>
>businessAreaFilter.addRightGeometry(filterFactory.createLiteralExpression(businessArea)))
>
>should do the trick (haven't tested the above, let me know).
>
>Cheers
>Andrea