Collect GTFS-RT data from a JSON feed at regular intervals

Usage

rt_collect_json(
  gtfs_rt_url,
  destination_file,
  header_key = "header",
  entity_key = "entity",
  fields_collect = c("id", "vehicle.trip.trip_id", "vehicle.position.latitude",
    "vehicle.position.longitude", "vehicle.position.speed", "vehicle.timestamp",
    "vehicle.current_status", "vehicle.current_stop_sequence", "vehicle.stop_id"),
  scrape_interval = 60,
  log_file = NA,
  headers = NULL
)

Arguments

gtfs_rt_url: String. URL of the GTFS-RT feed in JSON format.
destination_file: String. File to save the downloaded GTFS-RT data. Content is appended in each iteration.
header_key: String (Default "header"). Key in the JSON corresponding to the feed header. Set to NA if not present.
entity_key: String (Default "entity"). Key in the JSON corresponding to the feed entities. Set to NA if response is a flat list. Use "." for nested keys.
fields_collect: Character vector. Fields to extract from each entity in the feed. Use "." for nested keys.
scrape_interval: Integer (Default 60). Interval in seconds between each download. Negative to run only once.
log_file: String (Optional). Path to a log file to save download logs.
headers: Named list or character vector (Optional). Custom HTTP headers for credentials when accessing the GTFS-RT feed URL.

Value

String. The location of the file where data was collected.

Details

Downloads GTFS-RT data from the specified URL at regular intervals and saves them to the destination file.

This function will run indefinitely until manually stopped (CTRL + C).

Examples

# Create file
destination_file <- withr::local_tempfile(fileext = ".csv")

# Collect data
GTFShift::rt_collect_json(
  gtfs_rt_url = "https://go.tmlmobilidade.pt/hub/api/v1/realtime/vehicles/positions/gtfs",
  entity_key = "data.entity",
  destination_file = destination_file,
  scrape_interval = -1 # Negative to run only once
)
#> [2026-08-27 16:43:55] Starting GTFS-RT data collection from https://go.tmlmobilidade.pt/hub/api/v1/realtime/vehicles/positions/gtfs
#> [20260827_164355] Iteration 1 completed
#> [1] "/tmp/RtmpGgUISp/file1f216996f225.csv"

# Read data
collection <- read.csv(destination_file)

names(collection)
#> [1] "id"                            "vehicle.trip.trip_id"         
#> [3] "vehicle.position.latitude"     "vehicle.position.longitude"   
#> [5] "vehicle.position.speed"        "vehicle.timestamp"            
#> [7] "vehicle.current_status"        "vehicle.current_stop_sequence"
#> [9] "vehicle.stop_id"              

head(
  collection |>
    dplyr::select("vehicle.trip.trip_id", "vehicle.position.latitude", "vehicle.position.longitude")
)
#>               vehicle.trip.trip_id vehicle.position.latitude
#> 1 [F1M13][A2L1N]4704_0_2|2700|1735                  38.78615
#> 2 [F1M13][A2L1N]4600_0_1|2700|1700                  38.69729
#> 3  [0277F][BNA17]2537_0_1|1|3|1740                  38.86569
#> 4 [F1M13][A2L1N]4432_0_1|2700|1740                  38.52625
#> 5 [F1M13][A2L1N]4704_0_2|2700|1720                  38.70693
#> 6 [F1M13][A2L1N]4102_0_2|2700|1740                  38.68089
#>   vehicle.position.longitude
#> 1                  -9.091165
#> 2                  -8.944952
#> 3                  -9.060261
#> 4                  -8.891690
#> 5                  -8.960492
#> 6                  -8.985577