merge a list of gtfs files

!WARNING! only the tables: agency, stops, routes, trips, stop_times, calendar, calendar_dates, shapes, frequencies are processed, any other tables in the input timetables are passed through

Usage

gtfs_merge(
  gtfs_list,
  force = FALSE,
  quiet = TRUE,
  condenseServicePatterns = TRUE
)

Arguments

gtfs_list

a list of gtfs objects to be merged

force

logical, if TRUE duplicated values are merged taking the fist instance to be the correct instance, in most cases this is ok, but may cause some errors

quiet

logical, if TRUE less messages

condenseServicePatterns

logical, if TRUE service patterns across all routes are condensed into a unique set of patterns

Value

a single merged gtfs object

Details

if duplicate IDs are detected then completely new IDs for all rows will be generated in the output.

Feeds converted independently normally reuse the same ids - each regional TNDS conversion numbers its services from 1 - so the renumbering above is the usual path, not the exception. The renumbering keys on the input feed a row came from, tracked internally as `file_id`, which is therefore assigned from a feed's position in `gtfs_list` and means the same thing in every table.

It is not assigned per table. Doing that numbers each table over only the feeds that contain it, so one feed missing one optional table shifts the numbering of every later feed in that table alone, and rows are then renumbered against another feed's ids. A TNDS snapshot is the case that bites: its NCSD coach archive has no `calendar_dates`, and eight of the twelve regions had their cancellations applied to the preceding region's services.