how are the arc geometries are defined in your dataset. Generally the arc geometries are defined differently in respective GIS formats.
If the arcs are defined as tiny segments of linear objects, shapely should handle this.
If the arcs are defined using angle and radius then it needs to be simplified into tiny linear objects and pass into shapely.
One approach is to use the SQLite SQL dialect. It seems to work at least with a point shapefile where I digitized a few points, some of them in the same location.
ogrinfo -dialect sqlite -sql "select geometry, count(*) from duplicate_points group by geometry" duplicate_points.shp
Layer name: SELECT
Geometry: Unknown (any)
Feature Count: 4
I posted a similar message earlier in the “add comment” section, and was suggested to re-post this as an answer.
Deleting the \Roaming\QGIS folder worked a while, but the very same problems came back after I turned on all my plugins under the Plugins -> Manage and Install Plugins - > Installed. At this point I realized the problems may be related to the ...
I believe I have now resolved this.
The polygon in the .kml file is missing a closing point (i.e. the same as the first point). Adding the first point at the end of the coordinates tag, importing to Google Earth Pro and measuring the area produces 955km^2, much closer to that produced by the python code.
Got the solution on an issue of the shapely project on github https://github.com/Toblerity/Shapely/issues/738
There are no versions 1.6 distributions suitable for Windows on PyPI.
We can install old compatible version like 1.4.1 with this command.
pip install shapely==1.4.1