adjust_speed: Adjust the speeds of a gps-like table created with 'gtfs2gps'

In ipeaGIT/gtfs2gps: Converting Transport Data from GTFS Format to GPS-Like Records

Adjust the speeds of a gps-like table created with gtfs2gps

Description

Some GTFS.zip data sets might have quality issues, for example by assuming that a trip speed is unreasonably high (e.g. an urban bus running over 100 Km/h), or in other cases the 'timestamp' information might be missing for some route segments. This can lead a gps-like table to have 'NA' or unrealistic 'speed' and 'timestamp' values. This function allows the user to adjust the speed of trips and updates 'timestamp' values accordingly. The user can adjust the problematic speeds by either setting a custom constant value, or by considering the average of all valid trips speed (Default). The columns 'timestamp' and 'cumtime' are updated accordingly.

Usage

adjust_speed(
  gps_data,
  min_speed = 2,
  max_speed = 80,
  new_speed = NULL,
  clone = TRUE
)

Arguments

gps_data	A GPS-like data.table created with gtfs2gps.
min_speed	Minimum speed to be considered as valid. It can be a numeric (in km/h) or a units value able to be converted to km/h. Values below minimum speed will be adjusted. Defaults to 2 km/h.
max_speed	Maximum speed to be considered as valid. It can be a numeric (in km/h) or a units value able to be converted to km/h. Values above maximum speed will be adjusted. Defaults to 80 km/h.
new_speed	Speed to replace missing values as well as values outside min_speed and max_speed range. It can be a numeric (in km/h) or a units value able to be converted to km/h. By default, 'new_speed = NULL' and the function considers the average speed of the entire gps data.
clone	Use a copy of the gps_data? Defaults to TRUE.

Value

A GPS-like data with adjusted 'speed' values. The columns 'timestamp' and 'cumtime' are also updated accordingly.

Examples

poa <- read_gtfs(system.file("extdata/poa.zip", package="gtfs2gps")) |>
  gtfstools::filter_by_shape_id("T2-1") |>
  gtfstools::filter_by_weekday(c("monday", "wednesday")) |>
  filter_single_trip()

poa_gps <- gtfs2gps(poa)
poa_gps_new <- adjust_speed(poa_gps)

ipeaGIT/gtfs2gps documentation built on Oct. 13, 2024, 6:34 p.m.