Skip to contents

Derive trip terminals from supplied route geometries

Source: R/geometry_import.R
g2g_terminals_from_geometries.Rd

Determines the two terminals of a route from the route's own linestrings, with no GTFS feed involved: each direction's terminal is the first vertex of that direction's line, which is where a vehicle running that direction starts. The result feeds directly into terminals_data of g2g_extract_trips and g2g_extract_trips_and_stop_times.

Usage

g2g_terminals_from_geometries(geometries, route_id)

Arguments

geometries

The route geometries, in either of two forms:

  • a data.frame of vertices in long form, with columns route_id, direction, vertex_seq (the numeric order of the vertices within a direction), latitude and longitude; or

  • an sf object of LINESTRING or MULTILINESTRING geometries with route_id and direction columns (requires the 'sf' package). MULTILINESTRING parts are concatenated in part order.

route_id

A single route identifier present in geometries. The gps2gtfs pipeline models one route (two terminals) at a time.

Value

A data.table with columns terminal_id, latitude, longitude, direction, one row per direction. terminal_id equals direction.

Details

The terminal_id is the direction label itself. That is deliberate: g2g_stops_from_geometries labels stops with the same values, so the stop labels already are terminal IDs and no stop_direction_map is needed (the convention g2g_stops_from_gtfs documents).

Exactly two directions are required, because the terminal model is one route with two ends. A route drawn as one loop, or with a third branch variant, errors; use segmentation = "layover" for those. Two first vertices a few meters apart are not two ends of a line either, and warn.

See also

g2g_stops_from_geometries for the matching stops_data, and g2g_terminals_from_gtfs for the same table derived from a planned GTFS feed.

Examples

geometries <- data.frame(
  route_id = "r1",
  direction = rep(c("east", "west"), each = 3),
  vertex_seq = rep(1:3, times = 2),
  latitude = c(7.29, 7.30, 7.31, 7.31, 7.30, 7.29),
  longitude = c(80.63, 80.64, 80.65, 80.65, 80.64, 80.63)
)
g2g_terminals_from_geometries(geometries, route_id = "r1")
#>    terminal_id latitude longitude direction
#>         <char>    <num>     <num>    <char>
#> 1:        east     7.29     80.63      east
#> 2:        west     7.31     80.65      west