R/revenue_foregone.R

In grattan: Australian Tax Policy Analysis

#' Revenue foregone from a modelled sample file
#' @param dt A \code{data.table} from \code{\link{model_income_tax}}.
#' @param revenue_positive If \code{TRUE}, the default, tax increase (revenue) is positive and tax cuts are negative.
#' @param digits If not \code{NULL}, affects the print method of the value.
#' @export revenue_foregone

revenue_foregone <- function(dt, revenue_positive = TRUE, digits = NULL) {
  stopifnot(is.data.table(dt), 
            "WEIGHT" %in% names(dt),
            "new_tax" %in% names(dt),
            "baseline_tax" %in% names(dt))
  
  # nocov start 
  # Memory efficiency:
  if (min(.subset2(dt, "WEIGHT")) == max(.subset2(dt, "WEIGHT"))) {
    # is constant
    WEIGHT <- .subset2(dt, "WEIGHT")[1L]
    delta <- WEIGHT * as.double(.subset2(dt, "new_tax") - .subset2(dt, "baseline_tax"))
    
  } else if (getRversion() < "3.5.0") {
    
    # else will likely overflow
    new_tax <- as.double(.subset2(dt, "new_tax"))
    baseline_tax <- as.double(.subset2(dt, "baseline_tax"))
    WEIGHT <- as.double(.subset2(dt, "WEIGHT"))
    delta <- new_tax - baseline_tax
    delta <- WEIGHT * delta
    
  } else {
    delta <- .subset2(dt, "WEIGHT") * (.subset2(dt, "new_tax") - .subset2(dt, "baseline_tax"))
  }
  # nocov end
  out <- sum(delta)
  if (!revenue_positive) {
    out <- -out
  }
  class(out) <- "revenue_foregone"
  setattr(out, "digits", digits)
  out
}

#' @export
print.revenue_foregone <- function(x, ...) {
  pre <- 
    paste0(if (x < 0) {
      # minus sign
      "\u2212"
    },
    if_knitting_latex("\\$", "$"))
  
  if (x < 0) {
    x <- -x
  }
  
  d <- function(default) {
    if (is.null(attr(x, "digits"))) {
      default
    } else {
      attr(x, "digits")
    }
  }
  if (x > 10e9) {
    res <- paste0(pre, prettyNum(round(x / 1e9, d(0)), big.mark = ","),
                  if_knitting_latex("~billion", 
                                    " billion"))
  } else if (x > 1e9) {
    res <- paste0(pre, prettyNum(round(x / 1e9, d(1)), big.mark = ","),
                  if_knitting_latex("~billion", 
                                    " billion"))
  } else {
    res <- paste0(pre, prettyNum(round(x / 1e6, d(0)), big.mark = ","),
                  if_knitting_latex("~million", 
                                    " million"))
  }
  print(res)
}