R/splitDissolve.R

In jacpete/jpfxns: JP Functions

#' @title Fast Dissolve for Spatial* objects.
#'
#' @description
#' \code{splitDissolve} splits a Spatial* object from the (sp) package using
#' \code{seqSPDF}, and runs \code{sp::aggregate()} on the list.
#'
#' @details
#' This is a general wrapper for \code{sp::aggregate()} that allows
#' for quicker aggregation and fixed a ram leak issue caused by large datasets.
#'
#' @param input Spatial* object. SpatialPoints objects will be passed through
#' as is.
#' @param sep Passed to \code{seqSPDF()}. Default set to 1000.
#'
#' @return Returns a fully aggregated feature of Spatial* \code{input}
#'
#' @export
# @examples need to find test data and add examples
splitDissolve <- function(input, sep= 1000) {

  if (!grepl("Spatial", class(input))) {
    stop("\"input\" input not of a \'Spatial\' class")
  } else if (grepl("Point", class(input))) {
    warning("Cannot Dissolve SpatialPoints")
    return(input)
  }

  inputSplit <- seqSPDF(input, sep)

  dissolvedList <- lapply(inputSplit, function(i) {
    dissolved <- raster::aggregate(i, dissolve = T)
    return(dissolved)
  })

  dissolvedBind <- suppressWarnings(do.call(raster::bind, dissolvedList))

  dissolvedSP <- raster::aggregate(dissolvedBind, dissolve = T)

  return(dissolvedSP)
}