bus_collection_builder.py

from collections import defaultdict
from collections.abc import Generator, Sequence
from itertools import combinations, repeat
from math import radians
from operator import itemgetter

import networkx as nx
import numpy as np
from rapidfuzz.fuzz import token_ratio
from rapidfuzz.process import extract
from scipy.optimize import linear_sum_assignment
from sklearn.neighbors import BallTree

from config import BUS_COLLECTION_SEARCH_AREA
from cython_lib.geoutils import haversine_distance, radians_tuple
from models.fetch_relation import FetchRelationBusStop, FetchRelationBusStopCollection, PublicTransport
from utils import extract_numbers


def _pick_best(
    elements: list[FetchRelationBusStop],
) -> tuple[Sequence[FetchRelationBusStop], Sequence[FetchRelationBusStop]]:
    if not elements:
        return (), ()

    elements_explicit = tuple(e for e in elements if e.highway == 'bus_stop')
    elements_implicit = tuple(e for e in elements if e.highway != 'bus_stop')

    return elements_explicit, elements_implicit


def _assign(
    primary: Sequence[FetchRelationBusStop], elements: Sequence[FetchRelationBusStop], *, element_reuse: bool
) -> Generator[FetchRelationBusStop | None, None, None]:
    if len(elements) >= 2:
        # find the closest stop to each platform
        if len(elements) < len(primary):
            # disallow reuse of elements
            if not element_reuse:
                return repeat(None, len(primary))

            tree = BallTree(tuple(radians_tuple(e.latLng) for e in elements), metric='haversine')
            query_indices = tree.query(
                tuple(radians_tuple(p.latLng) for p in primary), k=1, return_distance=False, sort_results=False
            )

            return (elements[i] for i in query_indices[:, 0])

        # minimize the total distance between each platform and stop
        else:
            distance_matrix = np.zeros((len(primary), len(elements)))

            # compute the haversine distance between each platform and stop
            for i, p in enumerate(primary):
                for j, e in enumerate(elements):
                    distance_matrix[i, j] = haversine_distance(p.latLng, e.latLng)

            # use the Hungarian algorithm to find the optimal assignment
            row_ind, col_ind = linear_sum_assignment(distance_matrix)

            # ensure the assignments are sorted by platform indices
            assignments = sorted(zip(row_ind, col_ind))

            # get the assigned stop for each platform
            return (elements[j] for _, j in assignments)

    elif len(elements) == 1:
        # disallow reuse of elements
        if not element_reuse and len(primary) > 1:
            return repeat(None, len(primary))

        return repeat(elements[0], len(primary))
    else:
        return repeat(None, len(primary))


def build_bus_stop_collections(bus_stops: list[FetchRelationBusStop]) -> list[FetchRelationBusStopCollection]:
    # 1. group by area
    # 2. group by name in area
    # 3. discard unnamed if in area with named
    # 4. for each named group, pick best platform and best stop

    if not bus_stops:
        return []

    search_latLng = BUS_COLLECTION_SEARCH_AREA / 111_111
    search_latLng_rad = radians(search_latLng)

    bus_stops_coordinates = tuple(radians_tuple(bus_stop.latLng) for bus_stop in bus_stops)
    bus_stops_tree = BallTree(bus_stops_coordinates, metric='haversine')

    G = nx.Graph()

    query_indices, _ = bus_stops_tree.query_radius(
        bus_stops_coordinates, r=search_latLng_rad, return_distance=True, sort_results=True
    )

    # group by area
    for i in range(len(bus_stops)):
        G.add_edge(i, i)
    for query_group in query_indices:
        for i, j in combinations(query_group, 2):
            G.add_edge(i, j)

    collections: list[FetchRelationBusStopCollection] = []

    for component in nx.connected_components(G):
        # make area group from member indices
        area_group = tuple(bus_stops[member_index] for member_index in component)

        # group by name in area
        name_groups: dict[str, list[FetchRelationBusStop]] = defaultdict(list)

        for bus_stop in area_group:
            name_groups[bus_stop.groupName].append(bus_stop)

        # discard unnamed if in area with named
        if len(name_groups) > 1 and (unnamed := name_groups.get('')):
            unnamed = [s for s in unnamed if s.public_transport == PublicTransport.PLATFORM]  # never discard platforms
            if unnamed:
                name_groups[''] = unnamed
            else:
                name_groups.pop('')

        # expand short-name groups to long-name groups if possible
        if len(name_groups) > 1:
            expand_data = {
                expand_key: extract(expand_key, name_groups.keys(), scorer=token_ratio, score_cutoff=89)
                for expand_key in name_groups
            }

            expand_data = sorted(
                expand_data.items(), key=lambda t: (sum(map(itemgetter(1), t[1])), -len(t[0])), reverse=True
            )

            # pprint(expand_data)

            for expand_key, target_data in expand_data:
                expand_key_n = extract_numbers(expand_key)
                expand_group = name_groups[expand_key]
                expand_group_public_transports = {bus_stop.public_transport for bus_stop in expand_group}
                expanded = False

                for target_key, name_score, _ in target_data:
                    if target_key == expand_key:
                        continue

                    # expand non-numeric to numeric
                    #  or
                    # expand numeric to numeric when equal
                    if not expand_key_n.issubset(extract_numbers(target_key)):
                        continue

                    target_group = name_groups.get(target_key)

                    # skip if target_group was expanded/popped
                    if not target_group:
                        continue

                    target_group_public_transports = (bus_stop.public_transport for bus_stop in target_group)

                    # expand only if target doesn't share any public_transport types
                    if expand_group_public_transports.intersection(target_group_public_transports):
                        continue

                    print(
                        f'[COLL] [{name_score:5.1f}] Expanded {expand_key!r} to {target_key!r}, '
                        f'ID={expand_group[0].nice_id!r}'
                    )
                    target_group.extend(expand_group)
                    expanded = True

                if expanded:
                    name_groups.pop(expand_key)

        # for each named group, pick best platform and best stop
        for name_key, name_group in name_groups.items():
            platforms: list[FetchRelationBusStop] = []
            stops: list[FetchRelationBusStop] = []

            for bus_stop in name_group:
                if bus_stop.public_transport == PublicTransport.PLATFORM:
                    platforms.append(bus_stop)
                elif bus_stop.public_transport == PublicTransport.STOP_POSITION:
                    stops.append(bus_stop)
                else:
                    raise NotImplementedError(f'Unknown public transport type: {bus_stop.public_transport}')

            # for deterministic results
            platforms.sort(key=lambda p: p.id)
            stops.sort(key=lambda s: s.id)

            platforms_explicit, platforms_implicit = _pick_best(platforms)
            stops_explicit, stops_implicit = _pick_best(stops)

            if platforms_explicit and stops_explicit:
                collection_name = next(s.name for s in name_group if s.groupName == name_key)
                print(
                    f'🚧 Warning: Invalid explicit platforms and stops for {collection_name!r}, '
                    f'ID={stops_explicit[0].nice_id!r}'
                )

            if platforms_explicit:
                for platform, stop in zip(platforms_explicit, _assign(platforms_explicit, stops, element_reuse=True)):
                    collections.append(FetchRelationBusStopCollection(platform=platform, stop=stop))

                continue

            if stops_explicit:
                for stop, platform in zip(stops_explicit, _assign(stops_explicit, platforms, element_reuse=False)):
                    collections.append(FetchRelationBusStopCollection(platform=platform, stop=stop))

                continue

            if platforms_implicit and stops_implicit:
                for platform, stop in zip(platforms_implicit, _assign(platforms_implicit, stops, element_reuse=True)):
                    collections.append(FetchRelationBusStopCollection(platform=platform, stop=stop))

                continue

            if platforms_implicit:  # and not stops_implicit
                for platform in platforms_implicit:
                    collections.append(FetchRelationBusStopCollection(platform=platform, stop=None))

                continue

            if stops_implicit:  # and not platforms_implicit
                for stop in stops_implicit:
                    collections.append(FetchRelationBusStopCollection(platform=None, stop=stop))

                continue

    return collections