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November 25, 2019 15:19
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Linestring Polygon Overlay with Geopandas
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def line_polygon_intersection(line_df, poly_df): | |
column_geom_poly = poly_df._geometry_column_name | |
column_geom_line = line_df._geometry_column_name | |
spatial_index = line_df.sindex | |
bbox = poly_df.geometry.apply(lambda x: x.bounds) | |
sidx = bbox.apply(lambda x: list(spatial_index.intersection(x))) | |
nei = [] | |
for i, j in enumerate(sidx): | |
for k in j: | |
nei.append([i, k]) | |
if nei != []: | |
pairs = pd.DataFrame(nei, columns=["__idx1", "__idx2"]) | |
left = poly_df.geometry.take(pairs["__idx1"].values) | |
left.reset_index(drop=True, inplace=True) | |
right = line_df.geometry.take(pairs["__idx2"].values) | |
right.reset_index(drop=True, inplace=True) | |
intersections = pd.concat([left, right], 1) | |
intersections = intersections.apply(lambda x: x[column_geom_line].intersection(x[column_geom_poly]), 1) | |
intersections = gpd.GeoDataFrame(intersections, columns=['geometry']) | |
pairs_intersect = pairs[~intersections.is_empty] | |
geom_intersect = intersections[~intersections.is_empty].geometry | |
# merge data for intersecting geometries | |
line_df = line_df.reset_index(drop=True) | |
poly_df = poly_df.reset_index(drop=True) | |
dfinter = pairs_intersect.merge( | |
poly_df.drop(poly_df._geometry_column_name, axis=1), | |
left_on="__idx1", | |
right_index=True, | |
) | |
dfinter = dfinter.merge( | |
line_df, | |
left_on="__idx2", | |
right_index=True, | |
suffixes=["_1", "_2"], | |
) | |
result = gpd.GeoDataFrame(dfinter, geometry=geom_intersect, crs=poly_df.crs) | |
result.reset_index(drop=True, inplace=True) | |
result.drop(["__idx1", "__idx2"], axis=1, inplace=True) | |
return result |
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