在 Python 中合并两个 GEOJSON 多边形

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

这就是我使用 packages/modules json、geojson、shapely、pyproj 和来自 functools 的 partial 来做到这一点的方法：

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 中的这个示例似乎更加简洁：

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)

Answer 3

GeoPandas 中的 dissolve() 函数使这变得非常简单。例如，我有一个包含美国县（及其多边形）及其相应的天主教教区的 GeoDataFrame。我想创建多边形来显示每个县每个教区的轮廓。为此，我使用了以下代码：

diocese_boundaries = df_dioceses.dissolve(by = 'Diocese')

这返回了一个新的 DataFrame，其中包含每个教区的一行。每行都有一个新的几何列，其中包含每个教区的轮廓。

在 Python 中合并两个 GEOJSON 多边形

Merging two GEOJSON polygons in Python

python

geojson