R/UTMtoLongLat.R

In diegoalarc/GeodesiCL: Geometric Geodesy Functions

#' To convert from UTM to Geographic coordinate.
#'
#' With this function it is possible to convert from UTM coordinate
#' to Geographic coordinate. It is also possible to convert to other
#' coordinate reference systems by selecting their EPGS number.
#' Review notes and references.
#'
#' @param utm_df Point name, East and North UTM in a data.frame.
#' @param zone Select UTM zone to work.
#' @param hemisphere select between north or south (written in lowercase).
#' DEFAULT: "south"
#' @param crs EPGS number of the new coordinate reference system to transform.
#' DEFAULT: 4326 (WGS84)
#' @param digits Number of digits are \code{\link{round}ed} to. DEFAULT: 4
#'
#' @return a list with a data.frame and leaflet map.
#'
#' @seealso \code{data.frame}
#'
#' @export
#'
#' @note create data frame of epsg codes by epsg <- rgdal::make_EPSG()
#'
#' @references https://github.com/OSGeo/PROJ & https://github.com/cran/rgdal
#'
#' @examples
#' \donttest{
#' # Load test data from the package
#' csv <- system.file("extdata", "test.csv", package = "GeodesiCL")
#' data_test <- read_data(csv)
#'
#' # Zone
#' zone <- 19
#'
#' # Hemisphere could be "north" or "south"
#' hemisphere <- "south"
#'
#' value <- UTMtoLongLat(data_test, zone, hemisphere = "south", crs = 4326,
#'                       digits = 4)
#' print(value)
#' }
UTMtoLongLat <- function(utm_df, zone, hemisphere = "south", crs = 4326,
                         digits = 4){

  df <- data.frame(East = as.numeric(unlist(utm_df[,2])),
                   North = as.numeric(unlist(utm_df[,3])))
  sp::coordinates(df) <- c("East", "North")

  sp::proj4string(df) <- sp::CRS(paste0(
    "+proj=utm +zone=", zone,
    " +", hemisphere,
    " +datum=WGS84",
    " +units=m",
    " +no_defs +type=crs"))

  res <- sp::spTransform(df, sp::CRS(paste0("+init=epsg:",crs))) %>%
    data.frame()

  value <- tibble::as_tibble(as.data.frame(cbind(unlist(utm_df[,1]),
                                                 round(as.numeric(
                                                   unlist(res[,1])), digits),
                                                 round(as.numeric(
                                                   unlist(res[,2])), digits))))
  names(value) <- c("Pt", "Long", "Lat")

  map <- leaflet::leaflet(value) %>% leaflet::addTiles() %>%
    leaflet::addMarkers(data = value,
      as.numeric(value$Long), as.numeric(value$Lat),
      label = paste("Name: ", value$Pt, "<br>",
                    "Longitude: ", as.numeric(value$Long), "<br>",
                    "Latitude: ", as.numeric(value$Lat)) %>%
        lapply(htmltools::HTML)) %>%
    leaflet::addProviderTiles("OpenStreetMap", group = "OpenStreetMap") %>%
    leaflet::addProviderTiles("Stamen.Toner", group = "Stamen.Toner") %>%
    leaflet::addProviderTiles("Stamen.Terrain", group = "Stamen.Terrain") %>%
    leaflet::addProviderTiles("Esri.WorldStreetMap",
                              group = "Esri.WorldStreetMap") %>%
    leaflet::addProviderTiles("Wikimedia", group = "Wikimedia") %>%
    leaflet::addProviderTiles("CartoDB.Positron",
                              group = "CartoDB.Positron") %>%
    leaflet::addProviderTiles("Esri.WorldImagery",
                              group = "Esri.WorldImagery") %>%
    leaflet::addLayersControl(baseGroups = c("OpenStreetMap", "Stamen.Toner",
                                             "Stamen.Terrain",
                                             "Esri.WorldStreetMap",
                                             "Wikimedia", "CartoDB.Positron",
                                             "Esri.WorldImagery"),
                              position = "topleft")

  methods::show(map)
  return(value)
}