selection: Group or Select GTFS Records Without Filtering the Feed

In GTFSwizard: Creating, Exploring, and Manipulating GTFS Files

Group or Select GTFS Records Without Filtering the Feed

Description

Creates persistent selection metadata while leaving every GTFS table unchanged. Bare columns and computed values define groups, similarly to [dplyr::group_by()]. Logical expressions restrict the records represented by those groups.

Usage

selection(gtfs, ..., add = FALSE)

unselection(gtfs)

Arguments

gtfs	A GTFS object.
...	Unquoted grouping columns, computed grouping expressions, or logical selection expressions. Columns from 'stop_times', 'trips', 'routes', and 'stops' are available. A 'geometry' column is available for stop-based spatial predicates.
add	Logical. When 'TRUE', add the new grouping or selection expressions to an existing selection. When 'FALSE', replace it.

Details

A bare expression such as 'route_id' creates one group per route. Multiple grouping expressions create combinations, for example 'selection(gtfs, route_id, direction_id)'. Logical expressions such as 'route_id %in% c("1", "2")' restrict the records represented in the selection but do not remove rows from the GTFS feed.

Spatial expressions may use 'geometry' with '%intersects%', '%touches%', '%crosses%', '%within%', '%contains%', '%overlaps%', or '%equals%'.

Value

The unchanged feed with class 'wizardgtfs_selected' and a 'selection' attribute. The attribute contains 'groups', 'group_vars', selected route, trip, and stop IDs, and the original expressions.

See Also

[GTFSwizard::unselection()], [dplyr::group_by()]

Examples

grouped <- selection(for_rail_gtfs, route_id, direction_id)
attr(grouped, "selection")$groups

selected <- selection(
  for_rail_gtfs,
  route_id,
  stop_id %in% for_rail_gtfs$stops$stop_id[1:3]
)

bbox <- sf::st_bbox(
  c(xmin = -38.58, ymin = -3.81, xmax = -38.50, ymax = -3.75),
  crs = sf::st_crs(4326)
)
spatial <- selection(
  for_rail_gtfs,
  geometry %intersects% sf::st_as_sfc(bbox)
)

GTFSwizard documentation built on Aug. 21, 2026, 5:16 p.m.