From 6b5030fbb86adf24d48b0893d64214c2016765ae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Wiktor=20Niesiob=C4=99dzki?= <github@vink.pl>
Date: Sun, 10 Mar 2019 11:21:08 +0100
Subject: [PATCH] Example for converting Overpass response to shapely geometry
---
examples/overpass_geometry.py | 60 +++++++++++++++++++++++++++++++++++
1 file changed, 60 insertions(+)
create mode 100644 examples/overpass_geometry.py
diff --git a/examples/overpass_geometry.py b/examples/overpass_geometry.py
new file mode 100644
index 00000000..5c849f31
--- /dev/null
+++ b/examples/overpass_geometry.py
@@ -0,0 +1,60 @@
+"""
+Download example object from Overpass and turn it to shapely geometry and analyze shapely geometries
+"""
+import requests
+import shapely.ops
+import shapely.wkb
+
+import osmium as o
+
+wkb_factory = o.geom.WKBFactory()
+
+
+class GeometryHandler(o.SimpleHandler):
+ def __init__(self):
+ super(GeometryHandler, self).__init__()
+ self.__geometries = []
+
+ def way(self, w):
+ if 'amenity' in w.tags:
+ wkb = wkb_factory.create_linestring(w)
+ shape = shapely.wkb.loads(wkb, hex=True)
+ self.__geometries.append(shape)
+
+ @property
+ def geometries(self):
+ return self.__geometries
+
+
+def get_geometries(data):
+ # use MergeInputReader to sort input, so nodes will come first. Otherwise invalid locations could be passed
+ # in ways/relations GeometryHandler
+ mir = o.MergeInputReader()
+ mir.add_buffer(data, "osm") # Overpass returns data in osm format
+ gh = GeometryHandler()
+ # use memory index (flex_mem) for node locations cache. Use "sparse_file_array,<filename>" for file backed indices
+ mir.apply(gh, idx='flex_mem')
+ return gh.geometries
+
+
+def analyze(geoms):
+ """Union all geometries and get its centroid"""
+ print(shapely.ops.cascaded_union(geoms).centroid)
+
+
+def overpass_query():
+ resp = requests.post(url="https://overpass-api.de/api/interpreter",
+ data="[timeout:30];"
+ "way[amenity]"
+ "(41.886272470886496,12.476906776428223,41.89371621291292,12.507097721099854);"
+ "out body;"
+ ">;"
+ "out body;"
+ )
+ if resp.ok:
+ return resp.content
+ raise RuntimeError("Invalid response from Overpass: " + resp.text)
+
+
+if __name__ == '__main__':
+ analyze(get_geometries(overpass_query()))