This module contains scripts that reverse-geocode locations in London (within M25) using Turf.js with the data stored in ./data/geo/. The pure geographical operations are located at ./geo.js.
Convention: point = [lat, lng].
- gB(point) – Finds exact borough (exact at boundaries).
- gBD(point) – The above, represented by 3-letter code.
- gP(point) – Finds exact postal district (approximate at boundaries).
- gSt(point) – Finds nearest station marker (within 500m; TFL Tube Map (except Trams) and National Rail).
- gSu(point) – Finds nearest suburb marker (unbounded).
g(point)– (This has been moved toannotatein agent.js.) An endpoint: returns[postal district] [name], [3-letter borough code], where[name]is@ [nearest station]if a station is detected within 500m, else~ [nearest suburb].
Data comes from these sources.
- Postal Districts – https://www.doogal.co.uk/PostcodeDistricts.php
- Boroughs – https://data.gov.uk/dataset/local-authority-districts-december-2016-full-extent-boundaries-in-great-britain2
- Stations – OpenStreetMap (modified)
- Suburbs – OpenStreetMap (modified)
I processed the data as follows (the format is GeoJSON). I made up the borough codes myself.
- Postcodes.json contains polygons all postal districts in the areas [London postal area], WD, HA, EN, IG, RM, DA, BR, CR,SM, KT, TW, UB, modified by me to ensure Thames boundaries are on the Thames.
- Boroughs.json contains all local authority districts in the ceremonial counties Greater London, Buckinghamshire, Hertfordshire, Essex, Kent, Surrey, Berkshire.
- Stations.json contains all rail stations (except tram) within the M25; some may be missing (let me know).
- Suburbs.json contains place=suburb/town nodes from OSM, heavily modified by me to improve usefulness and accuracy.
The polygons in the polygon collections, Postcodes and Boroughs, have all been annotated with bounding boxes, at Feature.properties.bbox (computed using turf-bbox).
- turf-inside – Turf.js library to solve point-in-polygon via ray-casting.
- turf-distance – Turf.js library to find spherical distance between two points via Haversine formula.