Network from OSM download

This tutorial shows how to download and configure a road network from OpenStreetMap (OSM) and process it using the RA2CE library.

Step 1. Import the Required Packages

from pathlib import Path
import geopandas as gpd
from shapely.geometry.polygon import Polygon

from ra2ce.network import RoadTypeEnum
from ra2ce.network.network_config_data.enums.network_type_enum import NetworkTypeEnum
from ra2ce.network.network_config_data.network_config_data import NetworkSection, NetworkConfigData
from ra2ce.network.network_config_data.enums.source_enum import SourceEnum
from ra2ce.ra2ce_handler import Ra2ceHandler

Step 2. Define a Region of Interest

Create a bounding box for the area of interest and save it as a geojson file.

root_dir = Path("data", "network_from_OSM")
network_path = root_dir / "network"

polygon = Polygon([
    [4.925796685034555, 52.15567004009617],
    [4.925796685034555, 51.969875228118696],
    [5.263478289905265, 51.969875228118696],
    [5.263478289905265, 52.15567004009617],
    [4.925796685034555, 52.15567004009617]
])

# Convert polygon into geojson file
gdf_polygon = gpd.GeoDataFrame(index=[0], crs="EPSG:4326", geometry=[polygon])
gdf_polygon_path = network_path.joinpath("polygon.geojson")
gdf_polygon.to_file(gdf_polygon_path, driver="GeoJSON")

Step 3. Network Configuration

Define the network configuration using NetworkConfigData and NetworkSection classes., specifying OSM as the source and selecting road types.

network_section = NetworkSection(
    source=SourceEnum.OSM_DOWNLOAD,
    network_type=NetworkTypeEnum.DRIVE,
    road_types=[RoadTypeEnum.MOTORWAY, RoadTypeEnum.PRIMARY],
    polygon=gdf_polygon_path,
    save_gpkg=True,
)

network_config_data = NetworkConfigData(
    root_path=root_dir,
    static_path=root_dir / "static",
    network=network_section,
)

Step 4. Initialize and Configure RA2CE

Generate the network and store results in static/output_graph.

handler = Ra2ceHandler.from_config(network=network_config_data, analysis=None)
handler.configure()

Step 5. Load and Inspect the Output

path_output_graph = root_dir.joinpath("static", "output_graph")
base_graph_edges = path_output_graph.joinpath("base_graph_edges.gpkg")
edges_gdf = gpd.read_file(base_graph_edges, driver="GPKG")

base_graph_nodes = path_output_graph.joinpath("base_graph_nodes.gpkg")
nodes_gdf = gpd.read_file(base_graph_nodes, driver="GPKG")

Step 6. Plot Nodes and Edges

import matplotlib.pyplot as plt

fig, ax = plt.subplots(figsize=(15, 15))

# Plot edges first
baseplot = edges_gdf.plot(ax=ax, color="grey")

# Overlay nodes
nodes_gdf.plot(ax=baseplot, color="blue", markersize=20)

plt.show()