Prepare network and GTFS components for 'm4ra' queries.

This is a meta-function that calls the following functions:

• m4ra_weight_networks to generate several versions of the input street network weighted for different kinds of transport.

• m4ra_gtfs_traveltimes to generate

It also identifies the closest GTFS stops to every network point. The function stores several differently-weighted version of the street networks in a local cache directory defined by the user_cache_dir() function of the rappdirs package, or by a local environment parameter, "M4RA_CACHE_DIR", if set.

Usage

m4ra_prepare_data(
  net_sc = NULL,
  gtfs = NULL,
  city_name = NULL,
  planet_file = NULL,
  day = NULL,
  start_time_limits = NULL,
  final_mode = "foot",
  fast = FALSE,
  n_closest = 10L,
  batch_size = NULL,
  parking = FALSE,
  quiet = FALSE
)

Arguments

net_sc

Local file path to a silicate, "SC", format object containing network data used to generate weighted street networks.

gtfs

Local file path to a gtfsrouter object saved via saveRDS, containing GTFS (General Transit Feed Specification) data for network represented in net_sc. This .Rds object may include additional timetable or transfer information in addition to data represented in original zip-format data of provided GTFS feed.

city_name

Name of city used to name cached files.

planet_file

Optional file path to local .osm.pbf or .osm.bz2 file encompassing specified bounding box. If given, data are extracted with system-level calls to "osmium", which must be installed.

day

As for the 'gtfs_traveltimes' function of gtfsrouter, the day for which the matrix is to be calculated.

start_time_limits

As for the 'gtfs_traveltimes' function of gtfsrouter, a vector of two values specifying the earliest and latest departure times from each station.

final_mode

The mode of transport used for the final stage from GTFS stops to destination points.

fast

Values of TRUE generate potentially enormous matrices which may not fit in local memory. The default value of FALSE is generally safer, but calculation may take considerably longer.

n_closest

Final travel times to each destination point are calculated by tracing back times to this number of closest GTFS stops. Lower values will result in faster calculation times, yet with potentially inaccurate results.

batch_size

Default routine calculates full travel time matrices between all pairs of stops. For very large GTFS feeds, this matrix may not fit into memory, in which case this parameter can be set to a positive integer value to sequentially calculate only portions of the full matrix, before final re-assembly into single result.

parking

If TRUE, calculate local densities of parking availability and building volumes, and convert to a score used to calculate time penalties for automobile routing.

quiet

If FALSE, display progress information on screen.

See also

Other prep: m4ra_parking(), m4ra_times_to_gtfs_stops()