#' get_awsbike_files
#'
#' Returns list of URLs for each trip data file from nominated system
#'
#' @param name Name of the AWS bucket in which data are stored
#'
#' @return List of URLs used to download data
#'
#' @note bukets which work straight from AWS are
#' c ('tripdata', 'capitalbikeshare-data', 'hubway-data') for the cities
#' c ('ny', 'dc', 'bo'), respectively.
#'
#' @noRd
get_aws_bike_files <- function (bucket)
{
host <- "https://s3.amazonaws.com"
aws_url <- sprintf ("https://%s.s3.amazonaws.com", bucket)
doc <- httr::content (httr::GET (aws_url), encoding = 'UTF-8')
nodes <- xml2::xml_children (doc)
# NOTE: xml2::xml_find_all (doc, ".//Key") should work here but doesn't, so
# this manually does what that would do
files <- lapply (nodes, function (i)
if (grepl ('zip', i))
strsplit (strsplit (as.character (i),
"<Key>") [[1]] [2], "</Key>") [[1]] [1] )
# nyc citibike data has a redundamt file as first item
files <- unlist (files)
if (bucket == 'tripdata')
files <- files [2:length (files)]
paste0 (host, "/", bucket, "/", files)
}
#' get_la_bike_files
#'
#' Returns list of URLs for each trip data file from LA's Metro system
#'
#' @return List of URLs used to download data
#'
#' @note This system is brand new, and the data URLs will likely resolve to some
#' more systematic form very soon. This is just a temporary function providing
#' explicit URLs until that time.
#'
#' @noRd
get_la_bike_files <- function ()
{
host <- paste0 ("https://11ka1d3b35pv1aah0c3m9ced-wpengine.netdna-ssl.com/",
"wp-content/uploads/")
files <- c ("2016/10/MetroBikeShare_2016_Q3_trips.zip",
"2017/01/Metro_trips_Q4_2016.zip",
"2017/04/la_metro_gbfs_trips_Q1_2017.zip")
paste0 (host, files)
}
#' get_chicago_bike_files
#'
#' Returns list of URLs for each trip data file from Chicago's Divvy system
#'
#' @return List of URLs used to download data
#'
#' @note This is also an AWS, but it requires an OAuth key for direct access.
#' The AWS URLs are nevertheless listed in the main \code{html} file.
#'
#' @noRd
get_chicago_bike_files <- function ()
{
host <- "https://www.divvybikes.com/system-data"
. <- NULL # suppress R CMD check note
nodes <- httr::content (httr::GET (host), encoding = 'UTF-8') %>%
xml2::xml_find_all (., ".//aside") %>%
xml2::xml_find_all (., ".//a")
unique (xml2::xml_attr (nodes, "href"))
}
#' get_london_bike_files
#'
#' Returns list of URLs for each trip data file from London's Santander Cycles
#' system
#'
#' @return List of URLs used to download data
#'
#' @noRd
get_london_bike_files <- function ()
{
# First get list of base file names from AWS:
aws_url <- "https://s3-eu-west-1.amazonaws.com/cycling.data.tfl.gov.uk/"
doc <- httr::content (httr::GET (aws_url), encoding = 'UTF-8')
nodes <- xml2::xml_children (doc)
getflist <- function (nodes, type = 'zip')
{
f <- lapply (nodes, function (i) if (grepl (type, i))
strsplit (strsplit (as.character (i),
"<Key>") [[1]] [2], "</Key>") [[1]] [1] )
basename (unlist (f))
}
flist_zip <- getflist (nodes, type = 'zip')
flist_zip <- flist_zip [which (grepl ('usage', flist_zip))]
flist_csv <- getflist (nodes, type = 'csv')
# Then convert to tfl.gov.uk filenames
addr_base <- "http://cycling.data.tfl.gov.uk/usage-stats/"
paste0 (addr_base, c (flist_zip, flist_csv))
}
#' get_bike_files
#'
#' Returns list of URLs for each trip data file from nominated system
#'
#' @param city The city for which data are to be obtained
#'
#' @return List of URLs used to download data
#'
#' @noRd
get_bike_files <- function (city)
{
aws_cities <- c ('ny', 'dc', 'bo')
buckets <- c ('tripdata', 'capitalbikeshare-data', 'hubway-data')
if (city %in% aws_cities)
{
bucket <- buckets [match (city, aws_cities)]
files <- get_aws_bike_files (bucket)
} else if (city == 'la')
files <- get_la_bike_files ()
else if (city == 'ch')
files <- get_chicago_bike_files ()
else if (city == 'lo')
files <- get_london_bike_files ()
return (files)
}
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