[FWTools] GEOS contains fails after multiple iterations

[Bryan Keith]

Something I didn't mention: grid_py is a polygon shapefile so I use 
Centroid to get the point for the contains method.  If I use a point 
shapefile and just use myPTC = myFeature.GetGeometryRef(), then the 
script runs without a problem.

Bryan

Bryan Keith wrote:
> I'm having a problem with GEOS using Python and FWTools1.0.09a on 
> Windows 2000.  I've simplified my code to the point where I can 
> reproduce the error in this short script:
>
> import ogr
> #get valley file polygon
> myVFPY = ogr.CreateGeometryFromWkt("POLYGON ((0 0, 1 0, 1 1, 0 1, 0 0))")
> #get grid shapefile
> ogrSDS = ogr.Open("S:\\ProductionData\\Data\\GWModel", 1)
> ogrSLayer = ogrSDS.GetLayerByName("grid_py")
> #for i in range(ogrSLayer.GetFeatureCount()):
> #for i in range(10, 100):
> for i in range(100, 200):
>    print str(i)
>    myFeature = ogrSLayer.GetFeature(i)
>    myGeom = myFeature.GetGeometryRef()
>    myPTC = myGeom.Centroid()
>    #the following line fails at the 33rd time in the loop
>    if myVFPY.Contains(myPTC):
>        print "Contains myPTC"
>    else:
>        print "Does not contain myPTC"
>
>
> I get a "memory could not be read" error from the Contains() method 
> during the 33rd iteration of the loop.  The failure is not dependent 
> on the point as I've tested various sets of features in ogrSLayer.  
> The failure always happen the 33rd time through the loop.  Nor is the 
> failure dependent on the shapefile or the polygon.  I've tested 
> multiple of each.
>
> Anyone know what I'm doing wrong here?
>
> Bryan
>
> Bryan Keith
> GIS Specialist
> Geomega, Inc.
> Boulder, CO, USA
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