R/transfo_quali.R

In OTrecod: Data Fusion using Optimal Transportation Theory

#' transfo_quali()
#'
#' A function that transforms a factor of n(>1) levels in (n-1) binary variables.
#'
#' @aliases transfo_quali
#'
#' @param x a factor
#' @param labx a new label for the generated binary variables (By default the name of the factor is conserved)
#'
#' @return A matrix of (n-1) binary variables
#'
#' @author Gregory Guernec
#'
#' \email{otrecod.pkg@@gmail.com}
#'
#' @export
#'
#' @aliases transfo_quali
#'
#' @examples
#'
#' treat <- as.factor(c(rep("A", 10), rep("B", 15), rep("C", 12)))
#' treat_bin <- transfo_quali(treat, "trt")
#'
transfo_quali <- function(x, labx = NULL) {
  if (is.factor(x) == FALSE) {
    stop("Your variable needs to be convert in factor !")
  }

  lev_x <- levels(x)



  if (length(lev_x) == 1) {
    if (lev_x == "0") {
      x_bin <- as.matrix(as.numeric(x) - 1)
      colnames(x_bin)[1] <- labx
    } else if (lev_x != "0") {
      x_bin <- as.matrix(rep(1, length(x)))
      colnames(x_bin)[1] <- labx
    }
  } else {
    x_bin <- matrix(nrow = length(x), ncol = length(lev_x) - 1)

    for (j in 1:(length(lev_x) - 1)) {
      x_bin[, j] <- ifelse(x == lev_x[j + 1], 1, 0)
    }


    # Names of the binary variables

    colnames(x_bin) <- paste(labx, 2:(length(lev_x)), sep = "_")
  }

  return(x_bin)
}