568 lines
19 KiB
JavaScript
568 lines
19 KiB
JavaScript
/**
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* @fileoverview
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*
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* Extract static information about the TaM network from OpenStreetMap (OSM):
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* tram and bus lines, stops and routes.
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*
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* Functions in this file also report inconsistencies in OSM data.
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*
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* Because of the static nature of this data, it is cached in a
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* version-controlled file `network.json` next to this file. To update it,
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* run the `script/update-network.js` script.
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*/
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import * as turfHelpers from "@turf/helpers";
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import turfLength from "@turf/length";
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import * as util from "../util.js";
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import * as osm from "./sources/osm.js";
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/**
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* Route of a line of a transport network.
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* @typedef {Object} Route
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* @property {string} from Name of the starting point of the route.
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* @property {string} to Name of the ending point of the route.
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* @property {string?} via Optional name of a major intermediate
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* stop of the route.
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* @property {string} name Human-readable name of the line.
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*/
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/**
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* Line of a transport network.
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* @typedef {Object} Line
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* @property {string} color Hexadecimal color code of this line.
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* @property {Array.<Route>} routes Routes of this line.
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*/
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/**
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* Stop in a transport network (as a GeoJSON feature point).
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* @typedef {Object} Stop
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* @property {string} type Always equal to "Feature".
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* @property {string} id Stop identifier (unique in each network.).
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* @property {Object} properties
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* @property {string} properties.name Human-readable name of the stop.
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* @property {string} properties.node Associated node ID in OpenStreetMap.
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* @property {Array.<Array.[string,number]>} properties.routes
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* List of transport lines using this stop (as pairs of
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* line and route identifiers).
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* @property {Object} geometry
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* @property {string} geometry.type Always equal to "Point"
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* @property {Array.<number>} geometry.coordinates
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* Longitude and latitude of the stop point.
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*/
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/**
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* Planned segment routing between two stops of a transport network
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* (as a GeoJSON feature line string).
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* @typedef {Object} Segment
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* @property {string} type Always equal to "Feature".
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* @property {string} id Segment identifier (format: `{begin}-{end}`).
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* @property {Object} properties
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* @property {string} properties.begin ID of the stop at the beginning.
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* @property {string} properties.end ID of the stop at the end.
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* @property {number} properties.length Length of this segment (meters).
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* @property {Array.<Array.[string,number]>} properties.routes
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* List of transport lines using this segment (as pairs of
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* line identifiers and line direction numbers).
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* @property {Object} geometry
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* @property {string} geometry.type Always equal to "LineString".
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* @property {Array.<Array.<number>>} geometry.coordinates
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* Sequence of points forming this segment (as longitude/latitude pairs).
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*/
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/**
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* Edge of the graph for out-of-route navigation between stops.
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* @typedef {Object} NavigationEdge
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* @property {string} type Always equal to "Feature".
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* @property {Object} properties
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* @property {string} properties.begin ID of the stop or node at the beginning.
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* @property {string} properties.end ID of the stop or node at the end.
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* @property {number} properties.length Length of this edge (meters).
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* @property {Object} geometry
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* @property {string} geometry.type Always equal to "LineString".
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* @property {Array.<Array.<number>>} geometry.coordinates
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* Sequence of points forming this edge (as longitude/latitude pairs).
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*/
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/**
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* Information about a public transport network.
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* @typedef {Object} Network
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* @property {Object.<string,Stop>} stops List of stops.
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* @property {Object.<string,Line>} lines List of lines.
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* @property {Object.<string,Segment>} segments List of segments.
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* @property {Object.<string,Object.<string,NavigationEdge>>} navigation
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* Graph for out-of-route navigation between stops.
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*/
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/**
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* Retrieve raw routes, ways and stops from OpenStreetMap for the given
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* transport lines.
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* @param {Array.<string>} lineRefs List of lines to fetch.
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* @return {Array.<Object>} List of objects returned by OSM.
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*/
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// Retrieve routes, ways and stops from OpenStreetMap
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const queryLines = async lineRefs => {
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return (await osm.runQuery(`[out:json];
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// Find the public transport lines bearing the requested references
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relation[network="TaM"][type="route_master"][ref~"^(${lineRefs.join("|")})$"];
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(
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._;
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// Recursively fetch routes, ways and stops inside the lines
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>>;
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// Find adjacent tracks (used for out-of-route navigation)
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complete {
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way(around:0)[railway="tram"];
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};
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>;
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);
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out body qt;
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`)).elements;
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};
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/**
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* Assemble information about lines, stops and segments from the raw
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* OpenStreetMap data.
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* @param {Array.<Object>} elementsList List of nodes retrieved from OSM.
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* @param {Object.<string,Object>} elementsById OSM nodes indexed by their ID.
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* @return {Object} Assembled information about lines, stops and segments.
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*/
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const processRoutes = (elementsList, elementsById) => {
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const lines = {};
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const stops = {};
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const segments = {};
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const routeMasters = elementsList.filter(osm.isTransportLine);
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// Extract lines, associated stops and planned routes
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for (const routeMaster of routeMasters) {
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const lineRef = routeMaster.tags.ref;
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const color = routeMaster.tags.colour || "#000000";
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const routes = [];
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for (const [routeRef, data] of routeMaster.members.entries()) {
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const routeId = data.ref;
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const route = elementsById[routeId];
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const { from, via, to, name } = route.tags;
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const state = route.tags.state || "normal";
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// Add missing stops to the global stops object
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for (const { ref, role } of route.members) {
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if (role === "stop") {
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const stop = elementsById[ref];
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if (!("ref" in stop.tags)) {
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throw new Error(`Stop ${stop.id}
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(${osm.viewNode(stop.id)}) on line ${route.tags.name} is missing
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a “ref” tag`);
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}
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if (!(stop.tags.ref in stops)) {
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stops[stop.tags.ref] = turfHelpers.point([
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stop.lon,
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stop.lat
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], {
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name: stop.tags.name,
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node: ref.toString(),
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routes: [[lineRef, routeRef]],
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}, {
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id: stop.tags.ref,
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});
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} else {
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stops[stop.tags.ref].properties.routes.push([
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lineRef,
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routeRef
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]);
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}
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}
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}
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// Check that the route consists of a block of stops and platforms
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// followed by a block of routes as dictated by PTv2
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const relationPivot = route.members.findIndex(
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({ role }) => role === ""
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);
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if (!route.members.slice(0, relationPivot).every(
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({ role }) => role === "stop" || role === "platform"
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)) {
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throw new Error(`Members with invalid roles in between stops
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of ${name}`);
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}
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if (!route.members.slice(relationPivot).every(
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({ role }) => role === ""
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)) {
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throw new Error(`Members with invalid roles inside the path
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of ${name}`);
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}
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// List of stops in the route, expected to be in the timetable
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// order as per PTv2 and to be traversed in order by the sequence
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// of ways extracted below
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const lineStops = route.members.slice(0, relationPivot)
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.filter(({ role }) => role === "stop")
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.map(({ ref }) => ref);
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// List of ways making up the route’s path through its stops
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// with each way connected to the next through a single point
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const ways = route.members.slice(relationPivot)
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.map(({ ref }) => ref);
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// Merge all used ways in a single path
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let path = [];
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let currentNode = lineStops[0];
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for (let wayIndex = 0; wayIndex < ways.length; wayIndex += 1) {
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const way = elementsById[ways[wayIndex]];
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const { nodes: wayNodes } = way;
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const wayNodesSet = new Set(wayNodes);
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const curNodeIndex = wayNodes.indexOf(currentNode);
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// If not the last way, find a connection point to the next way
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// (there should be exactly one)
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let nextNode = null;
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let nextNodeIndex = null;
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if (wayIndex + 1 < ways.length) {
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const nextNodeCandidates = elementsById[ways[wayIndex + 1]]
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.nodes.filter(node => wayNodesSet.has(node));
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if (nextNodeCandidates.length !== 1) {
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throw new Error(`There should be exactly one point
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connecting way n°${wayIndex} and way n°${wayIndex + 1} in ${name},
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but there are ${nextNodeCandidates.length}`);
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}
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nextNode = nextNodeCandidates[0];
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nextNodeIndex = wayNodes.indexOf(nextNode);
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} else {
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nextNodeIndex = wayNodes.length;
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}
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if (curNodeIndex < nextNodeIndex) {
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// Use the way in its normal direction
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path = path.concat(
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wayNodes.slice(curNodeIndex, nextNodeIndex)
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);
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} else {
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// Use the way in the reverse direction
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if (osm.isOneWay(way)) {
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throw new Error(`Way n°${wayIndex} in
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${name} is one-way and cannot be used in reverse.`);
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}
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path = path.concat(
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wayNodes.slice(nextNodeIndex + 1, curNodeIndex + 1)
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.reverse()
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);
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}
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currentNode = nextNode;
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}
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// Split the path into segments between stops
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for (let stopIdx = 0; stopIdx + 1 < lineStops.length; ++stopIdx) {
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const begin = elementsById[lineStops[stopIdx]].tags.ref;
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const beginIdx = path.indexOf(lineStops[stopIdx]);
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const end = elementsById[lineStops[stopIdx + 1]].tags.ref;
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const endIdx = path.indexOf(
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lineStops[stopIdx + 1],
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beginIdx
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) + 1;
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const id = `${begin}-${end}`;
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const nodesIds = path.slice(beginIdx, endIdx);
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if (id in segments) {
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if (!util.arraysEqual(
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nodesIds,
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segments[id].properties.nodesIds
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)) {
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throw new Error(`Segment ${id} is defined as a
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different sequence of nodes in two or more lines.`);
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}
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segments[id].properties.routes.push([lineRef, routeRef]);
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} else {
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segments[id] = turfHelpers.lineString(nodesIds.map(
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nodeId => [
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elementsById[nodeId].lon,
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elementsById[nodeId].lat
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]
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), {
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// Keep track of the original sequence of nodes to
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// compare with duplicates
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nodesIds,
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routes: [[lineRef, routeRef]],
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begin: begin,
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end: end,
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}, { id });
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segments[id].properties.length = (
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1000 * turfLength(segments[id]));
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}
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}
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routes.push({
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from,
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via,
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to,
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name,
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state
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});
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}
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lines[lineRef] = {
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color,
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routes
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};
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}
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// Remove OSM nodes from segments that were only used for checking validity
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for (const segment of Object.values(segments)) {
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delete segment.properties.nodesIds;
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}
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return { lines, stops, segments };
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};
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/**
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* Create a graph for navigating between stops outside of
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* regular planned routes.
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* @property {Object.<string,Stop>} stops List of stops.
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* @param {Array.<Object>} elementsList List of nodes retrieved from OSM.
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* @param {Object.<string,Object>} elementsById OSM nodes indexed by their ID.
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* @return {Object.<string,Object.<string,NavigationEdge>} Resulting graph.
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*/
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const createNavigationGraph = (stops, elementsList, elementsById) => {
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// Graph of network stops and junctions
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const navigation = {};
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// Predecessors of each graph node
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const navigationReverse = {};
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// Stops indexed by their OSM ID instead of their network ID
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const stopsReverse = Object.fromEntries(
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Object.entries(stops).map(([id, stop]) => [stop.properties.node, id])
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);
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// Get the ID of a node in the navigation graph
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// (its network ID if it is a network object, otherwise its OSM id)
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const getNavigationId = objId => (
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objId in stopsReverse
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? stopsReverse[objId]
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: objId.toString()
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);
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// Get the OSM ID of a navigation object
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const getOSMId = navId => (
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navId in stops
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? stops[navId].properties.node
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: navId
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);
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// Create graph nodes from OSM nodes
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for (const obj of elementsList) {
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if (obj.type === "node") {
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navigation[getNavigationId(obj.id)] = {};
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navigationReverse[getNavigationId(obj.id)] = {};
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}
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}
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// Link up graph edges with OSM ways
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for (const obj of elementsList) {
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if (obj.type === "way") {
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const oneWay = osm.isOneWay(obj);
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const pairs = obj.nodes.slice(0, -1).map(
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(node, i) => [
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getNavigationId(node),
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getNavigationId(obj.nodes[i + 1]),
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]
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);
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for (const [from, to] of pairs) {
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navigation[from][to] = [from, to];
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navigationReverse[to][from] = true;
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if (!oneWay) {
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navigation[to][from] = [to, from];
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navigationReverse[from][to] = true;
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}
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}
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}
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}
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// Mark nodes of the graph to be kept
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const nodesToKeep = {};
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for (const nodeId in navigation) {
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if (nodeId in stops) {
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// Keep stop nodes
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nodesToKeep[nodeId] = true;
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continue;
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}
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const entries = new Set(Object.keys(navigationReverse[nodeId]));
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const exits = new Set(Object.keys(navigation[nodeId]));
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// Keep split nodes, i.e. nodes with at least two exit nodes
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// and one entry node that are all distinct from each other
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if (entries.size >= 1) {
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if (exits.size >= 3) {
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nodesToKeep[nodeId] = true;
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continue;
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}
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if (exits.size === 2) {
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for (const entry of entries) {
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if (!exits.has(entry)) {
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nodesToKeep[nodeId] = true;
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continue;
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}
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}
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}
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}
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// Keep junction nodes, i.e. nodes with at least two entry nodes
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// and one exit node that are all distinct from each other
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if (exits.size >= 1) {
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if (entries.size >= 3) {
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nodesToKeep[nodeId] = true;
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continue;
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}
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if (entries.size === 2) {
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for (const exit of exits) {
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if (!entries.has(exit)) {
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nodesToKeep[nodeId] = true;
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continue;
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}
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}
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}
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}
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}
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// Compress edges between nodes of interest
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for (const beginId in nodesToKeep) {
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const begin = navigation[beginId];
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const stack = [];
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const parent = {[beginId]: beginId};
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for (const succId in begin) {
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stack.push(succId);
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parent[succId] = beginId;
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}
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while (stack.length > 0) {
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const endId = stack.pop();
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const end = navigation[endId];
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if (endId in nodesToKeep) {
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if (endId in begin) {
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continue;
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}
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const reversePath = [endId];
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let trackback = parent[endId];
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let oneWay = !(trackback in end);
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while (trackback !== beginId) {
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reversePath.push(trackback);
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oneWay = oneWay || !(parent[trackback] in navigation[trackback]);
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delete navigation[trackback];
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trackback = parent[trackback];
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}
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reversePath.push(beginId);
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const forwardPath = [...reversePath];
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forwardPath.reverse();
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delete begin[forwardPath[1]];
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if (!(endId in begin)) {
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begin[endId] = forwardPath;
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}
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if (!oneWay) {
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delete end[reversePath[1]];
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if (!(beginId in end)) {
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end[beginId] = reversePath;
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}
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}
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} else {
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let isFirst = true;
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for (const succId in end) {
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if (succId !== parent[endId]) {
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if (isFirst) {
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parent[succId] = endId;
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stack.push(succId);
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isFirst = false;
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} else {
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throw new Error(`Multiple successors in \
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non-junction node ${endId}`);
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}
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}
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}
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if (isFirst) {
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// Reached a dead-end: remove the path
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let trackback = endId;
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while (parent[trackback] !== beginId) {
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delete navigation[trackback];
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trackback = parent[trackback];
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}
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delete navigation[trackback];
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delete begin[trackback];
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}
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}
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}
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}
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// Convert graph edges to GeoJSON line strings
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for (const [beginId, begin] of Object.entries(navigation)) {
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for (const endId in begin) {
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begin[endId] = turfHelpers.lineString(begin[endId].map(
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nodeId => [
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elementsById[getOSMId(nodeId)].lon,
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elementsById[getOSMId(nodeId)].lat
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]
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), {
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begin: beginId,
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end: endId,
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});
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begin[endId].properties.length = 1000 * turfLength(begin[endId]);
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}
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}
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return navigation;
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};
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/**
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* Fetch information about the network.
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* @param {Array.<string>} lineRefs List of lines to fetch.
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||
* @returns {Network} Network metadata extracted from OSM.
|
||
*/
|
||
export const fetch = async lineRefs => {
|
||
const elementsList = await queryLines(lineRefs);
|
||
const elementsById = elementsList.reduce((prev, elt) => {
|
||
prev[elt.id] = elt;
|
||
return prev;
|
||
}, {});
|
||
|
||
const { lines, stops, segments } = processRoutes(elementsList, elementsById);
|
||
const navigation = createNavigationGraph(stops, elementsList, elementsById);
|
||
|
||
return { navigation, lines, stops, segments };
|
||
};
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