R/get_coord_from_string.R

In bczernecki/climate: Interface to Download Meteorological (and Hydrological) Datasets

#' Getting coordinates from a string provided by the Ogimet web portal
#'
#' Internal function for cleaning coordinates' metadata provided by Ogimet
#' @param txt string with coordinates from Ogimet
#' @param pattern which element (Longitude or Latitude) to extract
#'
#' @format The returned object is the geographic coordinates using WGS84 (EPSG:4326) in decimal format.
#' Negative values mean western or southern Hemisphere
#' @keywords internal
#' @noRd

get_coord_from_string = function(txt, pattern = "Longitude") {
  tt = gregexpr(pattern, txt)
  start = tt[[1]][1] + attributes(tt[[1]])$match.length + 1
  tmp = trimws(substr(txt, start = start, stop = start + 8))
  tmp = strsplit(tmp, "-")[[1]]
  hemisphere = gsub("[0-9]", "", strsplit(tmp, "-")[2])
  hemisphere = gsub(".*?(\\b[A-Za-z0-9 ]+\\b).*", "\\1", hemisphere)

  tmp = suppressWarnings(as.numeric(gsub("([0-9]+).*$", "\\1", strsplit(tmp, "-"))))

  wsp = suppressWarnings(as.numeric(tmp)[1] + (as.numeric(tmp)[2] * 5 / 3) / 100)

  if (hemisphere %in% c("W", "S")) {
    wsp = wsp*-1
  }
return(wsp)
}