R/tradeValue.R

In pik-piam/magpie4: MAgPIE outputs R package for MAgPIE version 4.x

#' @title tradeValue
#' @description Calculates the value of traded goods based on a gdx file
#'
#' @export
#'
#' @param gdx GDX file
#' @param file a file name the output should be written to using write.magpie
#' @param level Level of regional aggregation ("reg", "glo", "regglo")
#' @param products Selection of products (either by naming products, e.g. "tece", or naming a set,e.g."kcr")
#' @param product_aggr aggregate over products or not (boolean)
#' @param type exports-imports ("net-exports"), gross imports ("imports") or
#' gross exports ("exports"); only valid if relative=FALSE
#' @param glo_weight Decides the calculation of global prices.
#' Weighting schemes are applied for estimation of global producer price.
#' If \code{"export"} prices are calculated as average of regional exporters' prices,
#' weighted by the export volumes. If \code{"production"} (default),
#' prices are calculated as average of regional prices weighted by regional production.
#' Alternatively, if \code{"free_trade"},
#'  the global prices are directly taken from the shadow prices of the global trade constraint,
#' and no averaging is performed.
#'  Alternatively, if \code{"constant_prices_initial"} constant 1995
#' global prices for each commodity are used as weight.
#' @param relative if relative=TRUE, self sufficiencies are reported
#' (the amount of production divided by domestic demand)
#' @return A MAgPIE object containing the value of trade flows in Million of US dollars
#' @author Misko Stevanovic, Florian Humpenoeder, Edna J. Molina Bacca
#' @examples
#' \dontrun{
#' x <- tradeValue(gdx)
#' }
#'
#' @importFrom gdx expand.set
#' @importFrom magpiesets findset

tradeValue <- function(gdx, file = NULL, level = "reg", products = "k_trade", product_aggr = FALSE, #nolint
                        type = "net-exports", glo_weight = "export", relative = FALSE) { #nolint

  # case for highres runs without trade
  products <- readGDX(gdx, products, react = "silent")
  if(is.null(products)) products <- readGDX(gdx, "kall")

  # detailed products
  if (!all(products %in% readGDX(gdx, "kall"))) products <- readGDX(gdx, products)

  # Global prices use for calculation of absolute trade value or as weight for the relative case
  if (glo_weight == "constant_prices_initial") {

    gloP <- readGDX(gdx, "f15_prices_initial")[, , products]

  } else if  (glo_weight %in% c("production", "export", "free_trade")) {

    gloP <- prices(gdx, level = "glo", products = products, glo_weight = glo_weight)

  } else {
    stop("Price not supported")
  }


  if (relative) {

    production <- production(gdx, level = "reg", products = products, product_aggr = FALSE, attributes = "dm")
    demand <- dimSums(demand(gdx, level = "reg", products = products, product_aggr = FALSE, attributes = "dm"),
                      dim = 3.1)

    production <- production * gloP
    demand <- demand * gloP

    if (product_aggr) {
      production <- dimSums(production, dim = "kall")
      demand <- dimSums(demand, dim = "kall")
    }
    if (level == "glo") {
      production <- dimSums(production, dim = 1)
      demand <- dimSums(demand, dim = 1)
    }

    # Self-sufficiency per item and region
    out <- production / demand
    out[!is.finite(out)] <- 0

  } else {

    # regional trade flows
    volume <- trade(gdx, level = "reg", products = products, type = type)

    # intersection of products in prices  and volume
    items <- intersect(getNames(volume), getNames(gloP))
    gloAgg <- gloP[, , items]

    # value of trade flows
    out <- volume * gloAgg

    if (product_aggr) {
      out <- dimSums(out, dim = "kall")
    }

    if (level == "glo") {
      out <- dimSums(out, dim = 1)
    } else if (level == "regglo") {

      glo <- dimSums(out, dim = 1)
      getItems(glo, dim = 1) <- "GLO"
      out <- mbind(out, glo)

    } else if (level != "reg") {
      stop("level is not implemented yet")
    }
  }


  out(out, file)
}