def create_graph(response_jsons,
name='unnamed',
retain_all=True,
bidirectional=False):
"""
Create a networkx graph from Overpass API HTTP response objects.
Parameters
----------
response_jsons : list
list of dicts of JSON responses from from the Overpass API
name : string
the name of the graph
retain_all : bool
if True, return the entire graph even if it is not connected
bidirectional : bool
if True, create bidirectional edges for one-way streets
Returns
-------
networkx multidigraph
"""
# make sure we got data back from the server requests
elements = []
elements.extend(response_jsons['elements'])
if len(elements) < 1:
raise ox.EmptyOverpassResponse(
'There are no data elements in the response JSON objects')
# create the graph as a MultiDiGraph and set the original CRS to default_crs
G = nx.MultiDiGraph(name=name, crs=ox.settings.default_crs)
# extract nodes and paths from the downloaded osm data
nodes = {}
paths = {}
nodes_temp, paths_temp = parse_osm_nodes_paths(response_jsons)
for key, value in nodes_temp.items():
nodes[key] = value
for key, value in paths_temp.items():
paths[key] = value
# add each osm node to the graph
for node, data in nodes.items():
G.add_node(node, **data)
# add each osm way (aka, path) to the graph
G = ox.add_paths(G, paths, bidirectional=bidirectional)
# retain only the largest connected component, if caller did not
# set retain_all=True
if not retain_all:
G = ox.get_largest_component(G)
# add length (great circle distance between nodes) attribute to each edge to
# use as weight
if len(G.edges) > 0:
G = ox.add_edge_lengths(G)
return G
def route_from_relation(relation, nodes, paths):
"""
Construct a route given the OSM relation.
:param dict relation: OSM relation corresponding to the route.
:param dict nodes: a lookup dictionary of the graph nodes.
:param dict paths: a lookup dictionary of the graph edges.
:returns: a tuple of line name and a multigraph.
"""
route_nodes = {}
route_paths = {}
rel_tags = relation["tags"]
line = rel_tags.get("line") or rel_tags.get("ref")
tags = {
"line": line,
"name": rel_tags.get("name"),
"type": rel_tags.get("route")
}
route = networkx.MultiDiGraph(name=line, crs=osmnx.settings.default_crs)
for member in relation["members"]:
key = member["ref"]
if member["type"] == "node":
route_nodes[key] = nodes[key]
if member["type"] == "way":
path = paths[key].copy()
path.update(**tags)
if "nodes" not in path:
continue
route_paths[key] = path
for node_key in path["nodes"]:
route_nodes[node_key] = nodes[node_key]
if not route_paths:
return
for key, data in route_nodes.items():
route.add_node(key, **data)
route = osmnx.add_paths(route, route_paths)
route = osmnx.add_edge_lengths(route)
return line, route
