GeoPandas – How to Find and Remove Overlapping Polygons

geopandasintersectionoverlaypython

I have 2 data frames, let's say, df1 and df2. I need to find df1 polygons that overlay with df2 (the green line), and remove them from main dataframe df1.

I do not need to extract a overlaying part or create a new dataframe, I need to identify the ones which overlays in any cases and remove them. The result would be df1 with the removed polygons.

I tried to use GeoPandas intersect and overlay, however, could not find the solution. Both dataframes have the same coordinate system.

import pandas as pd
import geopandas as gpd

df1 = gpd.read_file(r'E:\...\dfs1.shp')
df2 = gpd.read_file(r'E:\...\dfs2.shp')

print(df1.crs, df1.crs)

res_intersection = gpd.overlay(df1, df2, how='intersection')

TypeError: keep_geom_type does not support None.

Best Answer

You can use spatial join:

import geopandas as gpd
    
df1 = gpd.read_file(r'/home/bera/Desktop/gistemp/greens.shp')
df2 = gpd.read_file(r'/home/bera/Desktop/gistemp/buildings.shp')
df2['savedindex']= df2.index #Save the index values as a new column

intersecting = df1.sjoin(df2, how='inner')['savedindex'] #Find the polygons that intersect. Keep savedindex as a series

df2 = df2[~df2.savedindex.isin(intersecting)] #Filter away these, "savedindex is not in intersecting"

df2.to_file(r'/home/bera/Desktop/gistemp/buildings_disjoint.shp')

Related Solutions

GeoPandas – Troubleshooting No Intersection Found Issue

Intersects is row-wise operation which aligns both GeoSeries and check is a geometry A in row 0 intersects geometry B in row 0. See the documentation on that: https://geopandas.readthedocs.io/en/stable/docs/reference/api/geopandas.GeoSeries.intersects.html#geopandas.GeoSeries.intersects

For check if there is any intersection, use spatial index.

import numpy as np

inp, res = regions.sindex.query_bulk(points.geometry, predicate='intersects')
points['intersects'] = np.isin(np.arange(0, len(points)), inp)

Regarding the CRS warning, just remove init part and pass it as a string.

regions=regions.to_crs('epsg:4326')
points=points.set_crs('epsg:4326')

query_bulk requires geopandas 0.8. You can check the docs - https://geopandas.readthedocs.io/en/stable/docs/reference/api/geopandas.sindex.SpatialIndex.query_bulk.html#geopandas.sindex.SpatialIndex.query_bulk

Python – How to Find and Exclude Polygons Using GeoPandas

You can clip the points using the smaller polygons, then subset the larger polygons using a lambda function to find which ones contain any remaining points, such as:

import geopandas as gpd

#read in data
large = gpd.read_file(r'./polys.shp')
small = gpd.read_file(r'./polys2.shp')
points = gpd.read_file(r'./points.shp')

#clip points using small polys
points_subset = gpd.clip(points,small)

#filter polys based on remaining points
polys_subset =large[large.geometry.apply(lambda x: points_subset.within(x).any())]

#write output 
polys_subset.to_file('./poly_subset.shp')

Input data:

With output in pink:

Best Answer

Related Solutions

GeoPandas – Troubleshooting No Intersection Found Issue

Python – How to Find and Exclude Polygons Using GeoPandas

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