def main(args):
with open(args.features) as fp:
collection = geojson.load(fp)
shapes = [shapely.geometry.shape(feature["geometry"]) for feature in collection["features"]]
del collection
graph = UndirectedGraph()
idx = make_index(shapes)
def buffered(shape):
projected = project(shape, "epsg:4326", "epsg:3395")
buffered = projected.buffer(args.threshold)
unprojected = project(buffered, "epsg:3395", "epsg:4326")
return unprojected
def unbuffered(shape):
projected = project(shape, "epsg:4326", "epsg:3395")
unbuffered = projected.buffer(-1 * args.threshold)
unprojected = project(unbuffered, "epsg:3395", "epsg:4326")
return unprojected
for i, shape in enumerate(tqdm(shapes, desc="Building graph", unit="shapes", ascii=True)):
embiggened = buffered(shape)
graph.add_edge(i, i)
nearest = [j for j in idx.intersection(embiggened.bounds, objects=False) if i != j]
for t in nearest:
if embiggened.intersects(shapes[t]):
graph.add_edge(i, t)
components = list(graph.components())
assert sum([len(v) for v in components]) == len(shapes), "components capture all shape indices"
features = []
for component in tqdm(components, desc="Merging components", unit="component", ascii=True):
embiggened = [buffered(shapes[v]) for v in component]
merged = unbuffered(union(embiggened))
if merged.is_valid:
# Orient exterior ring of the polygon in counter-clockwise direction.
merged = shapely.geometry.polygon.orient(merged, sign=1.0)
# equal-area projection; round to full m^2, we're not that precise anyway
area = int(round(project(merged, "epsg:4326", "esri:54009").area))
feature = geojson.Feature(geometry=shapely.geometry.mapping(merged), properties={"area": area})
features.append(feature)
else:
print("Warning: merged feature is not valid, skipping", file=sys.stderr)
collection = geojson.FeatureCollection(features)
with open(args.out, "w") as fp:
geojson.dump(collection, fp)
def unbuffered(shape):
projected = project(shape, 'epsg:4326', 'epsg:3395')
unbuffered = projected.buffer(-1 * args.threshold)
unprojected = project(unbuffered, 'epsg:3395', 'epsg:4326')
return unprojected
def unbuffered(shape):
projected = project(shape, "epsg:4326", "epsg:3395")
unbuffered = projected.buffer(-1 * args.threshold)
unprojected = project(unbuffered, "epsg:3395", "epsg:4326")
return unprojected
def unbuffered(shape):
projected = project(shape, 'epsg:4326', 'epsg:3395')
unbuffered = projected.buffer(-1 * args.threshold)
unprojected = project(unbuffered, 'epsg:3395', 'epsg:4326')
return unprojected