R/largeRem.R

In basilesimon/largeRem: Rounds a sum of shares (%) to integers with largest remainer method

#' Largest remainder method to round percentages
#'
#' This function helps rounding up our down a list of percentages
#' (that add up to 100) into a list of integers that still add up to 100
#' @param pcVec: a vector
#' @examples
#' b <- c(20.5,60.3,19.2)
#' largeRem(b)
#' [1] 21 60 19

#   Build and Reload Package:  'Cmd + Shift + B'
#   Check Package:             'Cmd + Shift + E'
#   Test Package:              'Cmd + Shift + T'

largeRem <- function(pcVec) {

  if(sum(pcVec) != 100) stop("The sum of the items in your column isn't equal to 100")

  # If the sum of our rounds() is 99, we need to add one;
  # if greater than 100, we need to substract one
  # In case of equality (eg c(33.33, 33.33, 33.33)) we pick one at random with sample()
  diffTo100 <- 100 - sum(as.integer(pcVec))
  if (diffTo100 == 1) {
    index <- which.max(pcVec %% 1)
  } else if (diffTo100 == -1)  {
    index <- which.min(pcVec %% 1)
  }

  if(length(unique(pcVec %% 1)) == 1) {
    index <- sample(1:length(pcVec), 1)
  }

  pcVec[index] <- pcVec[index] + diffTo100
  return(as.integer(pcVec))
}