Difference between OGRGeometry and Geometry in C++ and python

Question

According to the documentation, there is a python version of OGRGeometry's C++ class (http://www.gdal.org/ogr/classOGRGeometry.html) which is http://gdal.org/python/osgeo.ogr.Geometry-class.html

However, I don't understand why there is a lot of differences between these two class.

For instance, in Python there aren't any import method (importFromWkt).

Is it normal or maybe I'm on on the wrong way.

Thanks

Answer 1

As gene pointed out importing from Wkt is provide under the OGR namespace and not included in the geometry module of python. Well I am saying this is not a choice by the developer who wraps the python. Python gdal is a wrapper based on SWIG. When it comes to wrapping a C++ library using SWIG there are some technical limitations and people should go other way to get the functionality. In this case "pure virtual" nature of Geometry::ImportFromWkt is the reason. So the importFomWkt is ignored by SWIG and the for keeping the functionality probably a new python function is added in the OGR namespace and ofcourse with a different name "CreateGeometryFromWkt"

Answer 2

For instance, in Python there aren't any import method (importFromWkt).

??? -> Look at the ogr module content:

from osgeo import ogr
print dir(ogr)
[...,  'CreateGeometryFromJson', 'CreateGeometryFromWkb', 'CreateGeometryFromWkt','CreateGeometryFromGML',...]

and the Python GDAL/OGR Cookbook 1.0 documentation:

wkt = "POINT (1120351.5712494177 741921.4223245403)"
point = ogr.CreateGeometryFromWkt(wkt)
geojson = """{"type":"Point","coordinates":[108420.33,753808.59]}"""
point = ogr.CreateGeometryFromJson(geojson)
....