R/setdiff.R

In matlab2r: Translation Layer from MATLAB to R

#' @title Set differences of two arrays
#' @description Loosely replicates the behavior of the homonym Matlab function
#' @param A first array
#' @param B second array
#' @param legacy if `TRUE`, preserves the behavior of the setdiff function from
#' MATLAB R2012b and prior releases. (currently not supported)
#' @author Waldir Leoncio
#' @export
#' @return An array containing he elements which are in A but not in B
#' @examples
#' A <- c(3, 6, 2, 1, 5, 1, 1)
#' B <- c(2, 4, 6)
#' setdiff(A, B)
setdiff <- function(A, B, legacy = FALSE) {
  values <- vector(typeof(A))
  if (legacy) message("legacy=TRUE not supported. Ignoring.")
  if (is(A, "numeric") & is(B, "numeric")) {
    values <- sort(unique(A[is.na(match(A, B))]))
  } else if (is(A, "data.frame") & is(B, "data.frame")) {
    C <- A
    exclude_rows <- vector()
    for (r1 in seq_len(nrow(A))) {
      for (r2 in seq_len(nrow(B))) {
        if (all(A[r1, ] == B[r2, ])) {
          exclude_rows <- append(exclude_rows, r1)
        }
      }
    }
    values <- C[-exclude_rows, ]
  }
  return(values)
}