R/create_env_stack.R

In grgurev/sdmflowR: What the Package Does (One Line, Title Case)

#' Create raster stack from environmental data
#'
#' Create raster stack from environmental data so that raster stack by
#' providing folder where raster are stored and optionally subset of those
#' raster that needs processing. It is just a wrapper around raster::stack()
#' and used when you have subset of variables to try so that you can quickly
#' check for NAs with `check_na_data()` function or value extraction when
#' generating absences and psudoabsences
#'
#' @param folder_in filename (character) or Raster object. Supported file types
#' are the "native" raster package format and those that can be read via rgdal
#' @param env_subset vector of filenames without extension (character) that
#' will be processed and stacked
#'
#' @return Raster stack
#' @export
#' @importFrom magrittr "%>%"

create_env_stack = function(
  folder_in,
  env_subset = c()
) {
  # set magrittr dot variable to NULL
  . = NULL

  # message for the user
  cat("\nCreating stack from environmental data ... \n")

  # define pattern based on most often used formats
  pattern = "\\.bil$|\\.tif$|\\.asc$"

  # get the rasters and create raster stack
  stack = list.files(
    gsub(
      pattern = "/$",
      replacement = "",
      x = folder_in),
    pattern,
    full.names = TRUE
  ) %>%
    raster::stack()

  # check if subset is defined to return only subset rasters
  if (length(env_subset) != 0) {
    stack = raster::subset(
      x = stack,
      env_subset)
  }

  # set the crs of raster stack
  raster::crs(stack) = "+proj=longlat +datum=WGS84"
  return(stack)
}