R/rcbind.R

In mlr3misc: Helper Functions for 'mlr3'

#' @title Bind Columns by Reference
#'
#' @description
#' Performs [base::cbind()] on [data.tables][data.table::data.table()], possibly by reference.
#'
#' @param x ([data.table::data.table()])\cr
#'   [data.table::data.table()] to add columns to.
#' @param y ([data.table::data.table()])\cr
#'   [data.table::data.table()] to take columns from.
#'
#' @return ([data.table::data.table()]): Updated `x` .
#' @export
#' @examples
#' x = data.table::data.table(a = 1:3, b = 3:1)
#' y = data.table::data.table(c = runif(3))
#' rcbind(x, y)
rcbind = function(x, y) {
  assert_data_table(x)
  assert_data_table(y)

  if (ncol(x) == 0L) {
    return(y)
  }

  if (ncol(y) == 0L) {
    return(x)
  }

  if (nrow(x) != nrow(y)) {
    stopf("Tables have different number of rows (x: %i, y: %i)",
      nrow(x), nrow(y))
  }

  dup = intersect(names(x), names(y))
  if (length(dup)) {
    stopf("Duplicated names: %s", str_collapse(dup))
  }

  ..y = NULL
  x[, (names(y)) := ..y][]
}