Add stop_area relations to a map

make_stop_areas.py

#!/usr/bin/env python3
import json
from lxml import etree
import sys
import kdtree
import math


QUERY = """
[out:json][timeout:25][bbox:{{bbox}}];
(
    node["railway"="subway_entrance"];
    node["station"="subway"];
    node["station"="light_rail"];
    node["public_transport"="stop_position"]["train"="yes"];
    node["public_transport"="stop_position"]["subway"="yes"];
    way["station"="subway"];
    relation["station"="subway"];
    way["railway"="platform"];
    relation["railway"="platform"];
);
out meta center qt;
rel(bn);out meta;
"""


class StationWrapper:
    def __init__(self, st):
        self.coords = (st['lon'], st['lat'])
        self.station = st

    def __len__(self):
        return 2

    def __getitem__(self, i):
        return self.coords[i]

    def distance(self, other):
        """Calculate distance in meters."""
        dx = math.radians(self[0] - other['lon']) * math.cos(
            0.5 * math.radians(self[1] + other['lat']))
        dy = math.radians(self[1] - other['lat'])
        return 6378137 * math.sqrt(dx*dx + dy*dy)


if len(sys.argv) < 2:
    print('Read a JSON from Overpass and output JOSM OSM XML with added stop_area relations')
    print('Usage: {} <export.json> [output.osm]'.format(sys.argv[0]))
    sys.exit(1)

with open(sys.argv[1], 'r') as f:
    src = json.load(f)['elements']

# Create a kd-tree out of subway stations
stations = kdtree.create(dimensions=2)
for el in src:
    if 'tags' in el and el['tags'].get('station', None) in ('subway', 'light_rail'):
        stations.add(StationWrapper(el))

# Populate a list of nearby subway exits and platforms for each station
MAX_DISTANCE = 300  # meters
stop_areas = {}
for el in src:
    if 'tags' not in el:
        continue
    if (el['tags'].get('railway', None) not in ('subway_entrance', 'platform') and
            el['tags'].get('public_transport', None) not in ('platform', 'stop_position')):
        continue
    coords = el.get('center', el)
    station = stations.search_nn((coords['lon'], coords['lat']))[0].data
    if station.distance(coords) < MAX_DISTANCE:
        k = (station.station['id'], station.station['tags']['name'])
        # Disregard exits and platforms that are differently named
        if el['tags'].get('name', k[1]) == k[1]:
            if k not in stop_areas:
                stop_areas[k] = [station.station]
            stop_areas[k].append(el)


# Find existing stop_area relations for stations and remove these stations
for el in src:
    if el['type'] == 'relation' and el['tags'].get('public_transport', None) == 'stop_area':
        found = False
        for m in el['members']:
            if found:
                break
            if m['type'] == 'node':  # Assuming all stations are nodes
                for st in stop_areas:
                    if m['ref'] == st[0]:
                        del stop_areas[st]
                        found = True
                        break

# Create OSM XML for new stop_area relations
root = etree.Element('osm', version='0.6')
rid = -1
for st, members in stop_areas.items():
    rel = etree.SubElement(root, 'relation', id=str(rid))
    rid -= 1
    etree.SubElement(rel, 'tag', k='type', v='public_transport')
    etree.SubElement(rel, 'tag', k='public_transport', v='stop_area')
    etree.SubElement(rel, 'tag', k='name', v=st[1])
    for m in members:
        if m['tags'].get('railway', m['tags'].get('public_transport', None)) == 'platform':
            role = 'platform'
        elif m['tags'].get('public_transport', None) == 'stop_position':
            role = 'stop'
        else:
            role = ''
        etree.SubElement(rel, 'member', ref=str(m['id']), type=m['type'], role=role)

# Add all downloaded elements
for el in src:
    obj = etree.SubElement(root, el['type'])
    for a in ('id', 'type', 'user', 'uid', 'version', 'changeset', 'timestamp', 'lat', 'lon'):
        if a in el:
            obj.set(a, str(el[a]))
    if 'tags' in el:
        for k, v in el['tags'].items():
            etree.SubElement(obj, 'tag', k=k, v=v)
    if 'members' in el:
        for m in el['members']:
            etree.SubElement(obj, 'member', ref=str(m['ref']),
                             type=m['type'], role=m.get('role', ''))
    if 'nodes' in el:
        for n in el['nodes']:
            etree.SubElement(obj, 'nd', ref=str(n))

result = etree.tostring(root, pretty_print=True)
if len(sys.argv) < 3:
    print(result.decode('utf-8'))
else:
    with open(sys.argv[2], 'wb') as f:
        f.write(result)