R/filenames_chelsa_future.R

In pastclim: Manipulate Time Series of Climate Reconstructions

#' Generate file names to download the chelsa future dataset
#'
#' This function creates a vector of paths needed to download the CHELSA future
#' dataset
#' @param dataset the name of the dataset of interest
#' @param bio_var the variable of interest
#' @returns a vector of times, one per band
#'
#' @keywords internal

filenames_chelsa_future <- function(dataset, bio_var) {
  # split the dataset name: model is element 3 and scenario element 4
  dataset_parsed <- unlist(strsplit(dataset, "_"))

  var_index <- substr(bio_var, nchar(bio_var) - 1, nchar(bio_var))

  if ("bio" == substr(bio_var, 1, 3)) {
    var_prefix <- "bio"
    var_index <- paste0(var_prefix, as.numeric(var_index)) # strip leading 0
  } else if (length(grep(pattern = "npp", bio_var))) {
    var_prefix <- "bio"
    var_index <- "npp"
  } else if (length(grep(pattern = "temperature_min", bio_var))) {
    var_prefix <- "tasmin"
    var_index <- paste0(var_prefix, "_", var_index)
  } else if (length(grep(pattern = "temperature_max", bio_var))) {
    var_prefix <- "tasmax"
    var_index <- paste0(var_prefix, "_", var_index)
  } else if ("tem" == substr(bio_var, 1, 3)) {
    var_prefix <- "tas"
    var_index <- paste0(var_prefix, "_", var_index)
  } else if ("pre" == substr(bio_var, 1, 3)) {
    var_prefix <- "pr"
    var_index <- paste0(var_prefix, "_", var_index)
  }
  time_steps <- c("2011-2040", "2041-2070", "2071-2100")
  time_steps_underscore <- c("2011_2040", "2041_2070", "2071_2100")
  chelsa_root <- "https://os.zhdk.cloud.switch.ch/chelsav2/GLOBAL/climatologies/" # nolint
  # compose download paths
  if (var_prefix == "bio") {
    chelsa_files <- paste0(
      chelsa_root,
      time_steps, "/", dataset_parsed[3], "/", dataset_parsed[4], "/",
      var_prefix, "/CHELSA_", var_index, "_", time_steps, "_",
      tolower(dataset_parsed[3]), "_", dataset_parsed[4], "_V.2.1.tif"
    )
  } else {
    chelsa_files <- paste0(
      chelsa_root,
      time_steps, "/", dataset_parsed[3], "/", dataset_parsed[4], "/",
      var_prefix, "/CHELSA_", tolower(dataset_parsed[3]),
      "_r1i1p1f1_w5e5_", dataset_parsed[4], "_", var_index,
      "_", time_steps_underscore, "_norm.tif"
    )
  }
  return(chelsa_files)
}