GeoPandas error - GEOSException: TopologyException: side location conflict

Question

I have a GeoDataFrame with fields: "Site","Group","Area", and "geometry" column with MultiPolygons. I try to unite rows based on the "Site" and "Group" columns using dissolve in this way:

gdf.dissolve(by=["Site","Group"],aggfunc={"Area":sum})

But I receive an error message:

GEOSException: TopologyException: side location conflict at 35.036441152893133 32.381401975779298. This can occur if the input geometry is invalid.

How can I locate the problematic Multipolygon / Polygon in GeoPandas?

Answer 1

Use .is_valid method:

import geopandas as gpd
import shapely

#Create a test dataframe
    #The first line is valid, the second is not, it starts and ends at the same point
wkts  = ["LINESTRING (30 10, 10 30, 40 40)", "LINESTRING (30 10, 30 10)"] 
geometries = [shapely.wkt.loads(x) for x in wkts] #Create shapely geometries
df = gpd.GeoDataFrame(geometry=geometries) #And a data frame

invalid = df.loc[~df.geometry.is_valid] #Select rows which are not (~) valid
#                                            geometry
#1  LINESTRING (30.00000 10.00000, 30.00000 10.00000)