[gdal-dev] [python-ogr] GetNumPoints from geometry

[Ari Jolma]

On 02/09/2011 04:19 PM, Frank Broniewski wrote:
> Hi,
>
> just a quick question: isn't GetNumPoints implemented on a geometry in 
> ogr python? 

There are OGR_G_GetPointCount in ogr_api.h and GetPointCount method in 
the Geometry class in Swig bindings.

Hm. It seems that NumPoints is the name of the method in the OGC simple 
features standard (it is defined for LineStrings).

Ari

> Neither GetNumPoints() nor getNumPoints() (small g) work.
> The passed in geometry is a geometry object from a
>
> geometry = feature.GetGeometryRef()
>
> call and the geometry is of type 'LINESTRING' taken from
>
> geometry.GetGeometryName() ...
>
>
> code:
> def line_nodes(geometry):
>     nodes = list()
>
>     for point_index in xrange(geometry.GetNumPoints()):
>         ogr_point = ogr.OGRPoint()
>         point = geometry.GetPoint(point_index, ogr_point)
>         dimenion = point.GetCoordinateDimension()
>         if dimension == 3:
>             list.append(point_index, point.GetX(), point.GetY(), 
> point.GetZ())
>         else:
>             list.append(point_index, point.GetX(), point.GetY())
>
>     return nodes
>
>
> raises an AttributeError
> ...
>     for point_index in xrange(geometry.getNumPoints()):
>   File "C:\Python26\lib\site-packages\osgeo\ogr.py", line 2672, in 
> <lambda>
>     __getattr__ = lambda self, name: _swig_getattr(self, Geometry, name)
>   File "C:\Python26\lib\site-packages\osgeo\ogr.py", line 34, in 
> _swig_getattr
>     raise AttributeError,name
> AttributeError: GetNumPoints
>
>
> Many thanks
>
> Frank
>