Worked like a charm... after I spent a few hours debugging geotools
exceptions, trying to figure out what values to plug into:
> ff.createAttributeExpression("THE_GEOM") - i.e. the column name in the
table
> gdf.setDistance(10) - this defaults to degrees, apparently, so one must
convert degrees to miles.
Thanks for your help. Again, this stuff would be great if there were more
samples of how to use it.
-Pete
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Cory
Horner
Sent: Tuesday, May 23, 2006 4:33 PM
To: [EMAIL PROTECTED]
Cc: [email protected]
Subject: Re: FW: [Geotools-gt2-users] How to use Filters? Expressions?
Peter Fay wrote:
>Cory,
>Since somehow your name is attached to API-Filters in the Module Matrix
>(http://docs.codehaus.org/display/GEOTOOLS/Module+Matrix), could you help
me
>out with my question below? (i.e. a code sample which creates a Filter to
>obtain a collection of all points within a radius of 10 miles... using
>version 2.2.C2)?
>
>It would be great to have more sample code of how to use filters and
>expressions...
>-Peter
>
>
Hi Peter,
We're still updating the snippets... I updated a couple of the
Filter-related ones today, but the rest will have to wait.
Here's a few breadcrumbs from my understanding of the code...
GeometryFactory gf = new GeometryFactory();
Geometry geometry = gf.createPoint(new Coordinate(50,50));
FilterFactory ff = FilterFactoryFinder.createFilterFactory();
GeometryDistanceFilter gdf = null;
try {
gdf =
ff.createGeometryDistanceFilter(FilterType.GEOMETRY_DWITHIN);
//instanciates CartesianDistanceFilter
//"radius"
gdf.setDistance(10); //this needs to be modified (in units
of CRS, geom?)
//add geom attribute
gdf.addLeftGeometry(ff.createAttributeExpression("THE_GEOM")); //name of
geometry attribute type
//add center of "circle"
gdf.addRightGeometry(ff.createLiteralExpression(geometry));
FeatureCollection allFeatures = null; //add
datastore/feature collection stuff here
System.out.println("First I have: "+allFeatures.size());
FeatureCollection lessFeatures = allFeatures.subCollection(gdf);
System.out.println("Now I have: "+lessFeatures.size());
} catch (IllegalFilterException e) {
e.printStackTrace();
}
I don't have a chance to test it right now... but let me know how it
goes and i'll add the result to the snippets section if it works out.
Cheers,
Cory.
----
Cory Horner
Refractions Research Inc.
http://www.refractions.net
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