Estimate stop coordinates from vehicle positions

Baseline-free helper: when no static GTFS feed exists, stop locations can be estimated from GTFS-Realtime Vehicle Positions that carry a stop_id annotation. Each stop's coordinates are the median position of the pings observed at it — by default only pings labeled STOPPED_AT, the most precise signal.

Usage

g2g_stops_from_positions(positions, statuses = "STOPPED_AT", min_obs = 3L)

Arguments

positions

A data.frame of vehicle positions (e.g. from gtfsrealtime::read_gtfsrt_positions() or g2g_clean_gps()) with columns stop_id, latitude, longitude, and optionally current_status.

statuses

Character vector of current_status values to use. Default "STOPPED_AT". Ignored (all stop_id-annotated pings used, with a message) when the current_status column is absent.

min_obs

Integer. Minimum number of pings required per stop; stops with fewer observations are dropped with a warning. Default 3.

Value

A data.table with columns stop_id, latitude, longitude, n_obs, sorted by stop_id.

Details

The result covers the stop_id/latitude/longitude columns of the stops_data input to g2g_extract_trips_and_stop_times; the direction label (starting terminal of trips serving the stop) must still be supplied, e.g. from the RT trip_id/direction_id annotations or a baseline feed. It also fills the spec-required stop_lat/stop_lon of a scaffolded stops.txt.