convert_stops_to_shapes: Convert stops into shapes

In gtfstools: General Transit Feed Specification (GTFS) Editing and Analysing Tools

Convert stops into shapes

Description

Creates shapes for the given trips, linking their consecutive stops along straight lines, and assigns them to the trips. Useful for feeds without shapes, or in which some trips are not linked to a shape.

Usage

convert_stops_to_shapes(gtfs, trip_id = NULL)

Arguments

gtfs	A GTFS object, as created by read_gtfs().
trip_id	A character vector including the trip_ids to get new shapes, which replace the shapes they are currently linked to. If NULL (the default), only the trips that are not linked to a usable shape get new shapes (see details).

Value

The GTFS object passed to the gtfs parameter, with the new shapes added to the shapes table (created if needed) and assigned to the trips in the trips table.

Details

The shape of a trip links its stops, in stop_sequence order, along straight lines. Stops without coordinates, or not listed in stops, are skipped. Trips that visit the same sequence of stops share the same shape. The new shapes get new shape_ids ("stops_shape_1", "stops_shape_2", etc.), different from any shape_id already listed in shapes or trips. Their shape_dist_traveled is not calculated, because the distance unit used by the feed is unknown, and the shape_dist_traveled of the stop_times entries of the trips that get new shapes, if present, is set to NA. Shapes no longer used by any trip are kept (please use remove_unused_ids() to remove them).

A shape is usable if it has at least two distinct points with coordinates. With trip_id = NULL, the trips that get new shapes are those not linked to a shape_id, or linked to a shape_id that is not listed in shapes or whose shape is not usable (all trips, if the feed doesn't have a shapes table). These are the trips that get_trip_length() and get_trip_geometry() can't measure along a shape.

Trips with fewer than two distinct stops with coordinates, or without stop_times entries, can't get a usable shape, so they keep their current shape_id, with a warning.

See Also

get_trip_geometry(), convert_sf_to_shapes(), remove_unused_ids()

Examples

library(dplyr)

data_path <- system.file("extdata/spo_gtfs.zip", package = "gtfstools")
gtfs <- read_gtfs(data_path)

# a feed without shapes gets one shape for each sequence of stops
gtfs$shapes <- NULL
new_gtfs <- convert_stops_to_shapes(gtfs)
head(new_gtfs$shapes)
new_gtfs$trips |>
  select(trip_id, shape_id) |>
  head()

gtfstools documentation built on Oct. 28, 2026, 5:13 p.m.