Asserts that a GTFS object is valid. Valid objects are those in which:
Every element is named.
Every element inherits from data.frames.
The exception to the second rule are objects that contain an element named
".". In such case, this element is actually composed by a named list of
elements who inherit from data.frames.
assert_gtfs(x)The same GTFS object passed to x.
Other constructors:
new_gtfs()
gtfs_path <- system.file("extdata/ggl_gtfs.zip", package = "gtfsio")
gtfs <- import_gtfs(gtfs_path)
gtfs <- assert_gtfs(gtfs)