R/is_region_series.R

In pastclim: Manipulate Time Series of Climate Reconstructions

#' Check the object is a valid region series
#'
#' A region series is a [`terra::SpatRasterDataset`] for which each sub-dataset
#' is a variable, and all variables have the same number of time steps.
#'
#' The standard test only checks that all sub-datasets (each of which is a
#' [`terra::SpatRaster`]) have the same number of layers. The more thorough test
#' (obtained with *strict=TRUE*) actually checks that all variables have the
#' same identical time steps by comparing the result of [terra::time()] applied
#' to each variable.
#'
#' @param x a [`terra::SpatRasterDataset`] representing a time series of
#'   regional reconstructions obtained from [region_series()].
#' @param strict a boolean defining whether to preform a thorough test (see
#'   description above for details).
#' @returns TRUE if the object is a region series
#'
#' @export

is_region_series <- function(x, strict = FALSE) {
  if (!inherits(x, "SpatRasterDataset")) {
    stop("x should be a SpatRasterDataset")
  }
  if (!strict) {
    return(length(unique(terra::nlyr(x))) == 1)
  } else {
    all_times <- list()
    for (i in terra::varnames(x)) {
      all_times[[i]] <- time_bp(x[i])
      # TODO we should check that each variable has years as its units
    }
    return(length(unique(all_times)) == 1)
  }
}