R/read_kml_file.R

In inbo/inborutils: Collection of Useful R Utilities

#' Extract date and coordinate information from Google Maps `kml` file
#'
#' @param filename (char) filename/path of the `kml` file
#'
#' @return `data.frame` with columns `datetime`, `x` (numeric), `y` (numeric)
#' @export
#'
#' @importFrom tidyr separate extract
#' @importFrom rlang .data
#' @importFrom lubridate dmy_hm
#'
#' @family download_functions
#'
#' @examples
#' \dontrun{
#' df <- read_kml_file("BE1002.kml")
#' }
read_kml_file <- function(filename) {
  kml_text <- readLines(filename)
  coords <- grep("<coordinates>", kml_text)
  coord <- as.data.frame(kml_text[coords + 1])
  colnames(coord) <- c("ruw")
  coords <- coord %>%
    separate(.data$ruw, c("x", "y", "z"), ",")

  date_ids <- grep("<name>", kml_text)
  dates_raw <- kml_text[date_ids][-1]
  dates_matched <- regmatches(
    dates_raw,
    regexpr(
      "[0-9]{2}/[0-9]{2}/[0-9]{4}.*[0-9]{2}:[0-9]{2}",
      dates_raw
    )
  )
  dates <- dmy_hm(dates_matched)
  datetime <- as.data.frame(dates)
  colnames(datetime) <- c("datetime")

  data <- cbind(datetime, coords[, 1:2])
  data$x <- as.numeric(data$x)
  data$y <- as.numeric(data$y)
  return(data)
}