R/initial.R

In shihs/LiUAdRLab6: The knapsack package

.check <- function(x, W) {
  #--------------------------------------------------------------------------------
  # Stop checking
  #--------------------------------------------------------------------------------
  if (!is.data.frame(x) || !is.numeric(W)) {
    stop("wrong input")
  }

  if (all(names(x) != c("w", "v"))) {
    stop("the name of columns have to be 'w' and 'v'")
  }

  if (!is.numeric(x$w) || !is.numeric(x$v)) {
    stop("the value of data.frame columns have to be positive number")
  }

  if (!all(x$w > 0) || !all(x$v > 0)) {
    stop("the value of data.frame columns have to be positive number")
  }

  # rowname for retrun elements
  rownames(x) <- 1:nrow(x)

  # delete the rows which weight are already over weight limit W
  i <- which(x$w > W)
  if (length(i) > 0) {
    x <- x[-i, ]
  }

  return(list(x, W))

}