| append_height | Add a column with height to GPS data |
| cpp_snap_points | Snap points to the closest points from another set |
| filter_by_agency_id | Filter GTFS data by agency ids |
| filter_by_shape_id | Filter GTFS data by shape ids |
| filter_day_period | Filter GTFS data within a period of the day |
| filter_single_trip | Filter GTFS trips in order to have one trip per shape_id |
| filter_valid_stop_times | Filter GTFS data using valid stop times |
| filter_week_days | Filter GTFS trips operating on week days |
| gps_as_sf | Convert GPS-like data.table to a Simple Feature object |
| gtfs2gps | Convert GTFS to GPS-like data given a spatial resolution |
| gtfs_shapes_as_sf | Convert GTFS shapes to simple feature object |
| gtfs_stops_as_sf | Convert GTFS stops to simple feature object |
| read_gtfs | Read GTFS data into a list of data.tables |
| remove_invalid | Remove invalid objects from GTFS data |
| test_gtfs_freq | Test whether a GTFS feed is frequency based |
| write_gtfs | Write GTFS data into a zip file |