GeoPandas – Merging Overlapping Features

geopandasoverlapping-features

I have a Shapefile with overlapping features.
Is there an easy way to merge them with geopandas?

I found a way with shapely, but I would like to do it with geopandas directly.

Best Answer

The GeoDataFrame

import geopandas as gpd
g1 = gpd.GeoDataFrame.from_file("poly_intersect.shp")
g1.shape
(4, 3)

1) You can use the itertools module

a) If you want to merge the intersections of the overlapping polygons

import itertools
geoms = g1['geometry'].tolist()
intersection_iter = gpd.GeoDataFrame(gpd.GeoSeries([poly[0].intersection(poly[1]) for poly in  itertools.combinations(geoms, 2) if poly[0].intersects(poly[1])]), columns=['geometry'])
intersection_iter.to_file("intersection_iter.shp")

Union

union_iter = intersection_iter.unary_union

b) If you want to merge the intersected polygons change intersection by union (all the polygons overlap in my example)

2) You can use GeoPandas Overlay

auto_inter = gpd.overlay(g1, g1, how='intersection')
auto_inter.shape
(7,4)

The resulting GeoDataframe

GeoPandas add the intersection geometries to the existing geometries, therefore

intersection = auto_inter[4:7]
intersection.to_file("intersection.shp")

Union

union = intersection.unary_union

b) use gpd.overlay(g1, g1, how='union')

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update link (28th October 2014) http://resources.arcgis.com/en/help/main/10.2/index.html#//00170000005n000000 Single Part & DISSOLVE_LINES enable in the geoprocessing tool.

Python – Merging Multiple Overlapping Lines

In Python using the fiona library to read the file and shapely to do the geometry operations it's easy to merge the geometries. For example:

import fiona
import shapely.geometry
import shapely.ops

with fiona.open(path) as src:
    merged_geometries = shapely.ops.linemerge([
        shapely.geometry.shape(feature["geometry"]) for feature in src])

The merged geometry will either be a LineString or a MultiLineString depending on whether a single contiguous line can be formed or not.

You can then write the result back out to a shapefile using fiona (see the docs on writing files), or really do whatever you like with it.

with fiona.open(path) as src:
    crs = src.crs
    driver = src.driver

schema = {
    "geometry": merged_geometries.geom_type,
    "properties": {
        "length": "float"
    }
}

with fiona.open(out_path, "w", driver=driver, crs=crs, schema=schema) as dest:
    dest.write({
        "geometry": shapely.geometry.mapping(merged_geometries),
        "id":"-1",
        "properties": {
            "length": merged_geometries.length
        }
    })

Best Answer

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