Question

有没有办法在python中合并两个重叠的GEOJSON多边形，返回一个合并的GEOJSON对象？

Answer 1

这就是我能够使用functools中的包/模块json，geojson，shapely，pyproj和partial来实现的：

import json
import geojson
from functools import partial
import pyproj
import shapely.geometry
import shapely.ops

# reading into two geojson objects, in a GCS (WGS84)
with open('file1.json') as geojson1:
    poly1_geojson = json.load(geojson1)

with open('file2.json') as geojson2:
    poly2_geojson = json.load(geojson2)


# pulling out the polygons
poly1 = shapely.geometry.asShape(poly1_geojson['features'][2]['geometry'])
poly2 = shapely.geometry.asShape(poly2_geojson['features'][2]['geometry'])

# checking to make sure they registered as polygons
print poly1.geom_type
print poly2.geom_type

# merging the polygons - they are feature collections, containing a point, a polyline, and a polygon - I extract the polygon
# for my purposes, they overlap, so merging produces a single polygon rather than a list of polygons
mergedPolygon = poly1.union(poly2)

# using geojson module to convert from WKT back into GeoJSON format
geojson_out = geojson.Feature(geometry=mergedPolygon, properties={})

# outputting the updated geojson file - for mapping/storage in its GCS format
with open('Merged_Polygon.json', 'w') as outfile:
    json.dump(geojson_out.geometry, outfile, indent=3, encoding="utf-8")
outfile.close()

# reprojecting the merged polygon to determine the correct area
# it is a polygon covering much of the US, and dervied form USGS data, so using Albers Equal Area
project = partial(
    pyproj.transform,
    pyproj.Proj(init='epsg:4326'),
    pyproj.Proj(init='epsg:5070'))

mergedPolygon_proj = shapely.ops.transform(project,mergedPolygon)

Answer 2

here中的示例似乎更为简洁：

from shapely.geometry import Polygon
from shapely.ops import cascaded_union

polygon1 = Polygon([(0, 0), (5, 3), (5, 0)])
polygon2 = Polygon([(0, 0), (3, 10), (3, 0)])

polygons = [polygon1, polygon2]

u = cascaded_union(polygons)

在Python中合并两个GEOJSON多边形

2 个答案: