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shortest-paths.py
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shortest-paths.py
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# calculate shortest paths between OD pairs
# in the map_speed_od postgis table
# update the shortest path geometry into the table
import requests, json, psycopg2
# get OD pairs from DB
conn_string = (
"host='localhost' dbname='' user='' password=''"
)
connection = psycopg2.connect(conn_string)
connection.autocommit = True
c = connection.cursor()
c.execute("""
SELECT
id,
ST_X(ST_StartPoint(vector)) AS lon1,
ST_Y(ST_StartPoint(vector)) AS lat1,
ST_X(ST_EndPoint(vector)) AS lon2,
ST_Y(ST_EndPoint(vector)) AS lat2
FROM map_speed_od
""")
# iterate over DB pairs
for (rid,lon1,lat1,lon2,lat2) in c.fetchall():
# request route for these points
options = {
'geometries':'geojson',
'overview':'full',
'steps':'false',
'annotations':'false'
}
response = requests.get(
('http://206.167.182.17:5000/route/v1/transit/'+str(lon1)+','+str(lat1)+';'+str(lon2)+','+str(lat2)),
params=options,
timeout=5
)
# parse the result
j = json.loads(response.text)
print json.dumps(j['routes'][0]['geometry'])
# insert the route result
c.execute("""
UPDATE map_speed_od
SET shortest_path = ST_SetSRID(ST_GeomFromGeoJSON(%s),4326)
WHERE id = %s;
""",
(json.dumps(j['routes'][0]['geometry']),rid,)
)