otp_create_surface: Creates a travel time surface (OTPv1 only).

In marcusyoung/otpr: An R Wrapper for the 'OpenTripPlanner' REST API

Creates a travel time surface (OTPv1 only).

Description

Creates a travel time surface for an origin point. A surface contains the travel time to every geographic coordinate that can be reached from that origin (up to a hard coded limit in OTP of 120 minutes). Optionally, the surface can be saved as a raster file (GeoTIFF) to a designated directory.

Usage

otp_create_surface(
  otpcon,
  getRaster = FALSE,
  rasterPath = tempdir(),
  fromPlace,
  mode = "TRANSIT",
  date = format(Sys.Date(), "%m-%d-%Y"),
  time = format(Sys.time(), "%H:%M:%S"),
  maxWalkDistance = NULL,
  walkReluctance = 2,
  waitReluctance = 1,
  transferPenalty = 0,
  minTransferTime = 0,
  batch = TRUE,
  arriveBy = TRUE,
  extra.params = list()
)

Arguments

otpcon	An OTP connection object produced by otp_connect.
getRaster	Logical. Whether or not to download a raster (geoTIFF) of the generated surface. Default FALSE.
rasterPath	Character. Path of a directory where the the surface raster should be saved if getRaster is TRUE. Default is tempdir(). Use forward slashes on Windows. The file will be named surface_id.tiff, with id replaced by the OTP id assigned to the surface.
fromPlace	Numeric vector, Latitude/Longitude pair, e.g. 'c(53.48805, -2.24258)'. This is the origin of the surface to be created.
mode	Character vector, mode(s) of travel. Valid values are: WALK, BICYCLE, CAR, TRANSIT, BUS, RAIL, TRAM, SUBWAY OR 'c("TRANSIT", "BICYCLE")'. TRANSIT will use all available transit modes. Default is CAR. WALK mode is automatically added for TRANSIT, BUS, RAIL, TRAM, and SUBWAY.
date	Character, must be in the format mm-dd-yyyy. This is the desired date of travel. Only relevant for transit modes. Default is the current system date.
time	Character, must be in the format hh:mm:ss. If arriveBy is FALSE (the default) this is the desired departure time, otherwise the desired arrival time. Only relevant for transit modes. Default is the current system time.
maxWalkDistance	Numeric. The maximum distance (in meters) that the user is willing to walk. Default is NULL (the parameter is not passed to the API and the OTP default of unlimited takes effect). This is a soft limit in OTPv1 and is ignored if the mode is WALK only. In OTPv2 this parameter imposes a hard limit on WALK, CAR and BICYCLE modes (see: http://docs.opentripplanner.org/en/latest/OTP2-MigrationGuide/#router-config).
walkReluctance	A single numeric value. A multiplier for how bad walking is compared to being in transit for equal lengths of time. Default = 2.
waitReluctance	A single numeric value. A multiplier for how bad waiting for a transit vehicle is compared to being on a transit vehicle. This should be greater than 1 and less than walkReluctance (see API docs). Default = 1.
transferPenalty	Integer. An additional penalty added to boardings after the first. The value is in OTP's internal weight units, which are roughly equivalent to seconds. Set this to a high value to discourage transfers. Default is 0.
minTransferTime	Integer. The minimum time, in seconds, between successive trips on different vehicles. This is designed to allow for imperfect schedule adherence. This is a minimum; transfers over longer distances might use a longer time. Default is 0.
batch	Logical. Set to TRUE by default. This is required to tell OTP to allow a query without the toPlace parameter. This is necessary as we want to build paths to all destinations from one origin.
arriveBy	Logical. Whether a trip should depart (FALSE) or arrive (TRUE) at the specified date and time. Default is FALSE.
extra.params	A list of any other parameters accepted by the OTP API SurfaceResource entry point. For advanced users. Be aware that otpr will carry out no validation of these additional parameters. They will be passed directly to the API.

Details

There are a few things to note regarding the raster image that OTP creates:

• The travel time cutoff for a surface is hard-coded within OTP at 120 minutes. Every grid cell within the extent of the graph that is 120 minutes travel time or beyond, or not accessible, is given the value of 120.

• Any grid cell outside of the extent of the network (i.e. unreachable) is given the value 128.

• It is advisable to interpret the raster of a surface in conjunction with results from evaluating the surface.

• OTP can take a while the first time a raster of a surface is generated after starting up. Subsequent rasters (even for different origins) are much faster to generate.

Value

Assuming no error, returns a list of 5 elements:

• errorId Will be "OK" if no error condition.

• surfaceId The id of the surface that was evaluated.

• surfaceRecord Details of the parameters used to create the surface.

• rasterDownload The path to the saved raster file (if getRaster was set to TRUE and a valid path was provided via rasterPath.)

• query The URL that was submitted to the OTP API.

If there is an error, a list containing 3 elements is returned:

• errorId The id code of the error.

• errorMessage The error message.

• query The URL that was submitted to the OTP API.

Examples

## Not run: 
otp_create_surface(otpcon, fromPlace = c(53.43329,-2.13357), mode = "TRANSIT",
maxWalkDistance = 1600, getRaster = TRUE)

otp_create_surface(otpcon, fromPlace = c(53.43329,-2.13357), date = "03-26-2019",
time = "08:00:00", mode = "BUS", maxWalkDistance = 1600, getRaster = TRUE,
rasterPath = "C:/temp")

## End(Not run)

marcusyoung/otpr documentation built on Aug. 22, 2022, 8:08 a.m.