API · Dash Sylvereye

Road network loading functions

Dash Sylvereye provides convenient functions to load and visualize OpenStreetMap (OSM) road network data retrieved with the excellent OSMnx library.

The data loading functions documented below are imported from the dash_sylvereye.utils module.

`load_from_osmnx_graph`

Use the load_from_osmnx_graph function to get the Dash Sylvereye's nodes_data and edges_data lists out of a NetworkX graph returned by the graph_from_place function of the OSMnx library.

load_from_osmnx_graph populates the following OSM node data (when available) found in the source graph under the nodes data key:

osmid (OSM ID)
highway
x (longitude)
y (latitude)

Content example of a nodes's data key:

{'highway': None,
 'osmid': 3015359332,
 'x': -100.4082449,
 'y': 20.5537155}

load_from_osmnx_graph also populates the following OSM edge data (when available) found in the source graph under the edges data key:

source_osmid (OSM ID of the edge's source node)
target_osmid (OSM ID of the edge's target node)
access
bridge
geometry (edge's LineString)
highway
junction
lanes
length
maxspeed
name
oneway
osmid
ref
service

Content example of an edge's data key:

{'access': None,
 'bridge': None,
 'geometry': 'LINESTRING (-100.3859634 20.5416189,  '
            '-100.3857662 20.5422811, -100.3856528  '
             '20.5432228, -100.38552 20.5441006,    '
             '-100.3854999 20.5444598, -100.3854269 '
             '20.5447641, -100.3851515 20.5451256)  ',
 'highway': 'unclassified',
 'id': None,
 'junction': None,
 'lanes': None,
 'length': '404.454',
 'maxspeed': None,
 'name': None,
 'oneway': 'False',
 'osmid': 351963225,
 'ref': None,
 'service': None,
 'source_osmid': '3577605387',
 'target_osmid': '3577605678'}

The following example retrieves the road network topology of Queretaro City with OSMnx and visualizes the data with the SylvereyeRoadNetwork component:

import osmnx as ox
from dash_html_components import Div
from dash_sylvereye import SylvereyeRoadNetwork
from dash_sylvereye.utils import load_from_osmnx_graph

OSMNX_QUERY = "Santiago de Queretaro, Queretaro, Mexico"

# retrieve road network topology and data from OSM
road_network = ox.graph_from_place(OSMNX_QUERY, network_type='drive') 
nodes_data, edges_data = load_from_osmnx_graph(road_network)

# dashboard setup
# 'app' is the app Dash object
app.layout = Div([
    SylvereyeRoadNetwork(
                         ...
                         nodes_data=nodes_data,
                         edges_data=edges_data
                         ...
                        )
                         
])

The following example will pretty print the OSM data in the Dash Sylvereye nodes and edges:

import pprint
import osmnx as ox
from dash_html_components import Div
from dash_sylvereye import SylvereyeRoadNetwork
from dash_sylvereye.utils import load_from_osmnx_graph

OSMNX_QUERY = "Santiago de Queretaro, Queretaro, Mexico"

# retrieve the road network topology and data from OSM
road_network = ox.graph_from_place(OSMNX_QUERY, network_type='drive') 
nodes_data, edges_data = load_from_osmnx_graph(road_network)

# print the data in nodes
for node in nodes_data:
    print(f"Node {node['osmid']}:")
    pprint.pprint(node['data'])

# print the data in edges
for edge in edges_data:
    print(f"Edge {edge['data']['source_osmid']} -> {edge['data']['target_osmid']}:")
    pprint.pprint(edge['data'])

Parameters

Name: g
Type: NetworkX graph

NetworkX graph returned by the graph_from_place function of the OSMnx library.

Returns

The function returns 2 values:

Type: list of list

List of Dash Sylvereye nodes.

Type: list of list

List of Dash Sylvereye edges.

`load_from_osmnx_graphml`

Use the load_from_osmnx_graphml function to get the Dash Sylvereye's nodes_data and edges_data from a GraphML file saved by the save_graphml function of the OSMnx library. It also returns the loaded road network as a NetworkX graph.

load_from_osmnx_graphml populates the following OSM node data (when available) found in the source graph under the nodes data key:

osmid (OSM ID)
highway
x (longitude)
y (latitude)

Content example of a nodes's data key:

{'highway': None,
 'osmid': 3015359332,
 'x': -100.4082449,
 'y': 20.5537155}

load_from_osmnx_graphml also populates the following OSM edge data (when available) found in the source graph under the edges data key:

source_osmid (OSM ID of the edge's source node)
target_osmid (OSM ID of the edge's target node)
access
bridge
geometry (edge's LineString)
highway
junction
lanes
length
maxspeed
name
oneway
osmid
ref
service

Content example of an edge's data key:

{'access': None,
 'bridge': None,
 'geometry': 'LINESTRING (-100.3859634 20.5416189,  '
            '-100.3857662 20.5422811, -100.3856528  '
             '20.5432228, -100.38552 20.5441006,    '
             '-100.3854999 20.5444598, -100.3854269 '
             '20.5447641, -100.3851515 20.5451256)  ',
 'highway': 'unclassified',
 'id': None,
 'junction': None,
 'lanes': None,
 'length': '404.454',
 'maxspeed': None,
 'name': None,
 'oneway': 'False',
 'osmid': 351963225,
 'ref': None,
 'service': None,
 'source_osmid': '3577605387',
 'target_osmid': '3577605678'}

The following example loads from disk the road network topology from the Queretaro.graphml file and visualizes the data with the SylvereyeRoadNetwork component:

import osmnx as ox
from dash_html_components import Div
from dash_sylvereye import SylvereyeRoadNetwork
from dash_sylvereye.utils import load_from_osmnx_graphml

GRAPHML_FILEN = "data/Queretaro.graphml"

# load road network topology and data from disk
nodes_data, edges_data, g = load_from_osmnx_graphml(GRAPHML_FILEN)

# print number of nodes and edges from the loaded NetworkX graph
print(f'Nodes: {g.number_of_nodes()} / Edges: {g.number_of_edges()}')

# dashboard setup
# 'app' is the app Dash object
app.layout = Div([
    SylvereyeRoadNetwork(
                         ...
                         nodes_data=nodes_data,
                         edges_data=edges_data
                         ...
                        )
                         
])

The following example will pretty print the OSM data in the Dash Sylvereye nodes and edges loaded from disk:

import pprint
import osmnx as ox
from dash_html_components import Div
from dash_sylvereye import SylvereyeRoadNetwork
from dash_sylvereye.utils import load_from_osmnx_graphml

GRAPHML_FILEN = "data/Queretaro.graphml"

# load road network topology and data from disk
nodes_data, edges_data, g = load_from_osmnx_graphml(GRAPHML_FILEN)

# print number of nodes and edges from the loaded NetworkX graph
print(f'Nodes: {g.number_of_nodes()} / Edges: {g.number_of_edges()}')

# print the data in nodes
for node in nodes_data:
    print(f"Node {node['osmid']}:")
    pprint.pprint(node['data'])

# print the data in edges
for edge in edges_data:
    print(f"Edge {edge['data']['source_osmid']} -> {edge['data']['target_osmid']}:")
    pprint.pprint(edge['data'])

Parameters

Name: filen
Type: str

File name of the GraphML file generated by the save_graphml function of the OSMnx library.

Returns

The function returns 3 values:

Type: list of list

List of Dash Sylvereye nodes.

Type: list of list

List of Dash Sylvereye edges.

Type: NetworkX graph.

NetworkX graph of the loaded road network.