Introduction to tidytransit
Tom Buckley
2023-06-23
Source:vignettes/introduction.Rmd
introduction.RmdInstallation & Dependencies
This package requires a working installation of sf.
# Once sf is installed, you can install from CRAN with:
install.packages('tidytransit')
# For the development version from Github:
# install.packages("devtools")
devtools::install_github("r-transit/tidytransit")The General Transit Feed Specification
The summary page for the GTFS standard is a good resource for more information on the standard.
GTFS feeds contain many linked tables about published transit schedules, service schedules, trips, stops, and routes. Below is a diagram of these relationships and tables:
Source: Wikimedia, user -stk.
Read a GTFS Feed
GTFS data come packaged as a zip file of comma separated tables in text form. The first thing tidytransit does is consolidate the reading of all those tables into a single R object, which contains a list of the tables in each feed.
Below we use the tidytransit read_gtfs function in order
to read a feed from the NYC MTA into R.
We use an example feed included in the package in the example below. But note that you can read directly from the New York City Metropolitan Transit Authority, as shown in the commented code below.
You can also read from any other URL. This is useful because there are many sources for GTFS data, and often the best source is transit service providers themselves. See the next section on “Finding More GTFS Feeds” for more sources of feeds.
# nyc <- read_gtfs("http://web.mta.info/developers/data/nyct/subway/google_transit.zip")
local_gtfs_path <- system.file("extdata",
"nyc_subway.zip",
package = "tidytransit")
nyc <- read_gtfs(local_gtfs_path)You can use summary to get an overview of the feed.
summary(nyc)## tidygtfs object
## files agency, routes, stop_times, trips, shapes, transfers, calendar, calendar_dates, stops
## agency MTA New York City Transit
## service from 2018-06-24 to 2018-11-03
## uses stop_times (no frequencies)
## # routes 22
## # trips 15911
## # stop_ids 1223
## # stop_names 306
## # shapes 215Each of the source tables for the GTFS feed is now available in the
nyc gtfs object. For example, stops:
head(nyc$stops)## # A tibble: 6 × 6
## stop_id stop_name stop_lat stop_lon location_type parent_station
## <chr> <chr> <dbl> <dbl> <int> <chr>
## 1 101 Van Cortlandt Park - 2… 40.9 -73.9 1 ""
## 2 101N Van Cortlandt Park - 2… 40.9 -73.9 0 "101"
## 3 101S Van Cortlandt Park - 2… 40.9 -73.9 0 "101"
## 4 103 238 St 40.9 -73.9 1 ""
## 5 103N 238 St 40.9 -73.9 0 "103"
## 6 103S 238 St 40.9 -73.9 0 "103"The tables available on each feed may vary. Below we can simply print the names of all the tables that were read in for this feed. Each of these is a table.
names(nyc)## [1] "trips" "stop_times" "agency" "calendar"
## [5] "calendar_dates" "stops" "routes" "shapes"
## [9] "transfers" "."Feed Validation Results
When reading a feed, it is checked against the GTFS specification,
and an attribute is added to the resultant object called
validation_result, which is a tibble about the files and
fields in the GTFS feed and how they compare to the specification.
You can get this tibble from the metadata about the feed.
## # A tibble: 6 × 8
## file file_spec file_provided_status field field_spec field_provided_status
## <chr> <chr> <lgl> <chr> <chr> <lgl>
## 1 agency Required TRUE agency… Condition… TRUE
## 2 agency Required TRUE agency… Required TRUE
## 3 agency Required TRUE agency… Required TRUE
## 4 agency Required TRUE agency… Required TRUE
## 5 agency Required TRUE agency… Optional TRUE
## 6 agency Required TRUE agency… Optional TRUE
## # ℹ 2 more variables: validation_status <chr>, validation_details <chr>Finding More GTFS Feeds
Feed registries
You can find more feeds on the following sites
There might be other feed registries available, depending on your area of interest. Transit agencies might also provide their feeds on their on website.
Using MobilityData
MobilityData.org provide a csv file with all their feed sources on their GitHub page.
You can load it in R and browse it as a data frame. Tidytransit cannot handle GTFS realtime data, so we can remove those entries.
MobilityData.csv = read.csv("https://storage.googleapis.com/storage/v1/b/mdb-csv/o/sources.csv?alt=media")
MobilityData_feedlist = MobilityData.csv %>%
as_tibble() %>%
filter(data_type == "gtfs")
str(MobilityData_feedlist)## tibble [1,610 × 26] (S3: tbl_df/tbl/data.frame)
## $ mdb_source_id : int [1:1610] 1 2 3 4 5 6 7 8 9 10 ...
## $ data_type : chr [1:1610] "gtfs" "gtfs" "gtfs" "gtfs" ...
## $ entity_type : chr [1:1610] "" "" "" "" ...
## $ location.country_code : chr [1:1610] "US" "CA" "CA" "US" ...
## $ location.subdivision_name : chr [1:1610] "Maine" "Ontario" "Ontario" "Ohio" ...
## $ location.municipality : chr [1:1610] "Casco Bay" "London" "Barrie" "Athens" ...
## $ provider : chr [1:1610] "Casco Bay Lines" "London Transit Commission" "Barrie Transit" "Athens Public Transit" ...
## $ name : chr [1:1610] "" "" "" "" ...
## $ note : chr [1:1610] "" "" "" "" ...
## $ feed_contact_email : chr [1:1610] "" "croy@londontransit.ca" "" "" ...
## $ static_reference : int [1:1610] NA NA NA NA NA NA NA NA NA NA ...
## $ urls.direct_download : chr [1:1610] "http://smttracker.com/downloads/gtfs/cascobaylines-portland-me-usa.zip" "http://www.londontransit.ca/gtfsfeed/google_transit.zip" "http://www.myridebarrie.ca/gtfs/Google_transit.zip" "https://transitfeeds.com/p/athens-public-transit/298/latest/download" ...
## $ urls.authentication_type : int [1:1610] NA 0 NA NA NA NA NA NA 0 NA ...
## $ urls.authentication_info : chr [1:1610] "" "" "" "" ...
## $ urls.api_key_parameter_name : chr [1:1610] "" "" "" "" ...
## $ urls.latest : chr [1:1610] "https://storage.googleapis.com/storage/v1/b/mdb-latest/o/us-maine-casco-bay-lines-gtfs-1.zip?alt=media" "https://storage.googleapis.com/storage/v1/b/mdb-latest/o/ca-ontario-london-transit-commission-gtfs-2.zip?alt=media" "https://storage.googleapis.com/storage/v1/b/mdb-latest/o/ca-ontario-barrie-transit-gtfs-3.zip?alt=media" "https://storage.googleapis.com/storage/v1/b/mdb-latest/o/us-ohio-athens-public-transit-gtfs-4.zip?alt=media" ...
## $ urls.license : chr [1:1610] "" "https://www.londontransit.ca/open-data/ltcs-open-data-terms-of-use/" "https://www.barrie.ca/services-payments/transportation-parking/barrie-transit/barrie-gtfs" "" ...
## $ location.bounding_box.minimum_latitude : num [1:1610] 43.7 42.9 44.3 39.3 44.1 ...
## $ location.bounding_box.maximum_latitude : num [1:1610] 43.7 43.1 44.4 39.4 45 ...
## $ location.bounding_box.minimum_longitude: num [1:1610] -70.2 -81.4 -79.7 -82.1 -75.8 ...
## $ location.bounding_box.maximum_longitude: num [1:1610] -70.1 -81.1 -79.6 -82 -74.6 ...
## $ location.bounding_box.extracted_on : chr [1:1610] "2022-02-22T19:51:22+00:00" "2022-02-22T19:51:34+00:00" "2022-03-01T22:43:25+00:00" "2022-03-23T14:43:11+00:00" ...
## $ status : chr [1:1610] "inactive" "" "" "deprecated" ...
## $ features : chr [1:1610] "" "" "" "" ...
## $ redirect.id : chr [1:1610] "" "" "" "1973" ...
## $ redirect.comment : chr [1:1610] "" "" "" "" ...There is a URL (column urls.direct_download) for each
feed, which can be used to read the feed for a given area directly into
R. For example:
gtfs_path_goldengate <- MobilityData_feedlist %>%
filter(provider == "Golden Gate Transit") %>%
pull(urls.direct_download)
gtfs_goldengate = read_gtfs(gtfs_path_goldengate)The MobilityData feedlist contains bounding box coordinates for a feed which can be used to give a basic impression of the location of feeds. Note that some bounding boxes might be wrong.
First, let’s create bounding box polygons.
# create a bounding box polygon from min/max corner coordinates
suppressPackageStartupMessages(library(sf))
bbox_polygon = function(lon_min, lon_max, lat_min, lat_max) {
corner_coords = matrix(
c(lon_min, lat_min,
lon_min, lat_max,
lon_max, lat_max,
lon_max, lat_min,
lon_min, lat_min),
ncol = 2, byrow = T
)
polyg = st_polygon(list(corner_coords))
return(st_sfc(polyg, crs = 4326))
}
# create bounding box polygon (only for reasonable values)
MobilityData_sf = MobilityData_feedlist %>%
filter(!is.na(location.bounding_box.minimum_longitude)) %>%
filter(location.bounding_box.minimum_latitude > -89) %>%
group_by(mdb_source_id) %>%
mutate(geometry = bbox_polygon(location.bounding_box.minimum_longitude,
location.bounding_box.maximum_longitude,
location.bounding_box.minimum_latitude,
location.bounding_box.maximum_latitude)) %>%
ungroup() %>% st_as_sf()These boxes could now be shown on an interactive map.
library(leaflet)
leaflet() %>%
addProviderTiles(provider = providers$CartoDB.Positron) %>%
addPolygons(data = MobilityData_sf, weight = 2,
fillOpacity = 0.1, label = substr(MobilityData_sf$provider, 0, 60))