R/download_worldclim_future.R

In EvolEcolGroup/pastclim: Manipulate Time Series of Palaeoclimate Reconstructions

#' Download the worldclim future time series.
#'
#' This function downloads annual and monthly variables from the WorldClim v2.1 dataset
#' for future projections.
#' 
#' Note: the data come as tiffs each containing all bio (or prec/temp)
#' variables for a given time step. From these, we generate a vrt per variable. So,
#' since we download the full set for a give variable type, we create all the vrts
#' for that variable type (e.g. all the bio). We use the filename to get the version
#' name, and then at the end to check that we did generate it correctly given our
#' programmatic way of creating the names of all vrt files.
#' @param dataset the name of the dataset
#' @param bio_var the variable name
#' @param filename ()
#' @returns TRUE if the requested worldclim variable was downloaded successfully
#' 
#' @keywords internal

download_worldclim_future <- function(dataset, bio_var, filename = NULL) {
  # extract the version from the filename
  version <- gsub("^.*_v([0-9]+\\.[0-9]+\\.[0-9]+)\\..*$", "\\1", filename)
  # compose download paths
    download_url <- filenames_worldclim_future(dataset=dataset,
                                            bio_var = bio_var)
    time_vector <- c(2030, 2050, 2070, 2090)
  
  # create band vectors
  # function to grab the number from the raster layer
  if (grepl("bio", bio_var)) {
    band_vector <- paste0("bio", sprintf("%02d", 1:19))
  } else {
    var_prefix <- substr(bio_var,nchar(bio_var)-1,nchar(bio_var))
    band_vector <- paste0(var_prefix, sprintf("%02d", 1:12))
  }

  # if we do not have a directory, create one
  worldclim_dir <- file.path(get_data_path(),"worldclim_2.1")
  if(!dir.exists(worldclim_dir)){
    dir.create(worldclim_dir)
  }

  # and now download the files (so the url is actually a local file)
  worldclim_url <- file.path(worldclim_dir,basename(download_url))
  download_res <- curl::multi_download(download_url,
                                       destfiles = worldclim_url#, resume = TRUE
  )
  if(any(!download_res$success)){
    stop("something went wrong downloading the data; try again")
  }


  # create a vrt for each variable
  for (i in seq_len(length(band_vector))){
    vrt_path <- file.path(get_data_path(), paste0(dataset,"_",band_vector[i],"_v",version,".vrt"))
    # create the vrt file
    # we capture warnings from the vrt to make sure that all is well
    # withCallingHandlers({
    #   vrt_path <- terra::vrt(x = worldclim_url,
    #                          filename = vrt_path,
    #                          options=c("-b", i,"-separate"), overwrite=TRUE, return_filename=TRUE)
    # }, warning = function(w) {
    #   if (!grepl("Only the first one",w)){
    #     file.remove(vrt_path)
    #     stop("vrt creation failed with ", w,"\n try to redownload this dataset")
    #   }
    #   invokeRestart("muffleWarning")
    # })
    
    withCallingHandlers({
      sf::gdal_utils(
        util = "buildvrt",
        source = worldclim_url,
        destination = vrt_path,
        options = c("-b", i,"-separate","-overwrite")
      )
    }, warning = function(w) {
      if (!grepl("Only the first one",w)){
        file.remove(vrt_path)
        stop("vrt creation failed with ", w,"\n try to redownload this dataset")
      }
      invokeRestart("muffleWarning")
    })
    
    
    ######################################################################
    # in gdal <3.8, the -b is ignored, and only the first band is used
    # so, we edit the SourceBand for each band
    x<- xml2::read_xml(vrt_path)
    band_nodes <- xml2::xml_find_all(x, ".//SourceBand")
    xml2::xml_text(band_nodes) <- as.character(i)
    xml2::write_xml(x, vrt_path)
    ## end of workaround
    ######################################################################
    
    # edit the vrt metadata
    edit_res <- vrt_set_meta(vrt_path = vrt_path, 
                 description = band_vector[i],
                 time_vector = time_vector,
                 time_bp = FALSE)
    if (!edit_res){
      file.remove(vrt_path)
      stop("something went wrong setting up this dataset", "\n the dataset will need downloading again")
    }
   }
  if (!file.exists(vrt_path)){
    stop("something went wrong setting up this dataset", "\n the dataset will need downloading again")
  }
  return(TRUE)
}