R/raster2magpie.R

In pik-piam/geodata: Landuse geodata library

### to do
# needs thorough checking whether it does what it should
# auto detection of years is not very elegant at the moment. First it trys to detect. If it has done then there is a 2. loop that does the replacement in this case
# add functionality for lists
# 



#' Convert raster data to MAgPIE object
#' 
#' Raster data (layers, bricks or stacks) from the raster package is converted
#' to a MAgPIE object. In the case of bricks and stacks different data
#' dimensions are created for the different layers. Data should be in lat/long
#' with a 0.5x0.5 degree resolution, and have at least the extent of MAgPIE
#' data (-180,180,-56,83.5)
#' 
#' 
#' @usage raster2magpie(x, detect_years=TRUE)
#' @param x A raster object
#' @param detect_years The function can try to detect years (4 digit numbers)
#' in the names of the raster, and use them as the temporal dimension
#' @return A MAgPIE object with the data of the raster at the geographic center
#' of each MAgIE cell
#' @author Ulrich Kreidenweis
#' @examples
#' 
#' \dontrun{
#' r <- raster::raster()
#' raster::res(r) <- 0.5
#' raster::values(r) <- 1:(raster::ncell(r))
#' m <- raster2magpie(r)
#' head(m)
#' }
#' 
#' @export raster2magpie
#' @importFrom raster res couldBeLonLat
#' @importFrom magclass new.magpie
raster2magpie <- function(x, detect_years=TRUE) {
  
#  if(class(x)!="RasterLayer") stop("x has to be a RasterLayer")
  if(any(res(x) != 0.5)) warning ("Raster resolution should be 0.5 x 0.5, if it is not only information from the center of MAgPIE cells will be considered")
  if(!couldBeLonLat(x, warnings=F)) stop("Raster has to be in long/lat")

  ## try to detect years in the names. But be careful, that the data is then filled to the magpie object correctly!!
  # requirements
  
  years <- NULL
  names <- names(x)
  
  dat <- as.matrix(raster::extract(x, ludata::getCoordinates(degree=T, order="magpie")))
  
  if (detect_years){
    ## if names contain any 4 digit num
    
    if (all(grepl("[0-9]{4}",names(x)))) {
      years <- as.numeric(gsub(".*([0-9]{4}).*", "\\1", names(x))) # the numbers
      names <- gsub("\\.y[0-9]{4}\\D*","",names(x))
      
      if(length(unique(paste0(names, years)))!=length(names(x))) warning("Combination of detected years and names didn't produce enough unique entries. Switch of detect_years.")
    
      colnames(dat) <- paste(names, years, sep=".")
      #detected_years <- TRUE
    } #else {detected_years <- FALSE}
  } 

  #tmp <- new.magpie(cells_and_regions = paste(geodatadata$region,1:59199,sep="."),years = years,names = names,fill = NA)
  tmp <- new.magpie(cells_and_regions = paste(magclass:::magclassdata$half_deg$region,1:59199,sep="."), years = unique(years), names = unique(names), fill = NA)
  
  # geodatadata is part of magclassdata. Should better come from magclass package via a function, so if it is changed there, would be still correct here
  
  tmp[,,] <- dat
  
  attr(tmp, "coordinates") <- ludata::getCoordinates(degree = T)
  
  return(tmp)
}