R/rflip.R

In mobilizingcs/mobilizr: Functions for the Mobilize Introduction to Data Science course.

#' Coin flip.
#'
#' Flip a coin 2000 times or fewer.
#'
#' @param n Integer. The number of times to flip the coin.
#' @param prob Number between 0 and 1. The probability of getting a "head".
#'   Default value is 0.5.
#' @param quiet Logical. Should a message be printed with the output? Default is
#'   \code{FALSE}, meaning a message will be printed.
#' @param verbose Logical. The opposite of quiet from above. Should a message be
#'   printed? Default value is \code{TRUE}. Note, either quiet or verbose can be
#'   specified, but not both.
#'
#' @examples
#' # Basic usage. Note the printed output.
#' rflip()
#'
#' # The printed output can be turned off using either method:
#' rflip(quiet = TRUE)
#' rflip(verbose = FALSE)
#'
#' # Flip an unfair coin many times
#' flips <- rflip(100, prob = 0.35)
#' flips
#'
#' # The actual output is embedded as an attribute
#' attr(flips, "sequence")
#'
#' # Create a bargraph of the output
#' flips_output <- attr(flips, "sequence")
#' bargraph(~flips_output)
#'
#' @export

rflip <- function(n = 1, prob = 0.5, quiet = FALSE, verbose = !quiet) {
  # Prevent students from flipping more than 2000 coins to avoid them hogging computational resources
  if (n > 2000) {
    stop("Number of flips should be less than or equal to 2000")
  } else {
    # Flip the coins
    result <- mosaic::rflip(n = n, prob = prob, quiet = quiet, verbose = verbose)

    class(result) <- "cointoss"
    return(result)
  }
}

#' @rdname rflip
#' @param x an object
#' @param \dots additional arguments
#' @export

print.cointoss <- function(x, ...) {
  heads <- as.numeric(x)
  other <- attributes(x)
  if (other$verbose) {
    cat(paste("\nFlipping a coin ",
      other$n,
      " time", ifelse(other$n > 1, "s", ""),
      " [ Prob(Heads) = ", other$prob, " ] ...\n",
      sep = ""
    ))
  }

  if (attributes(x)$verbose) {
    cat("\n")
    # print(other$sequence)
    cat(paste(
      strwrap(paste(other$sequence, collapse = " ")),
      collapse = "\n"
    ))
    cat("\n")
    cat(paste("\nNumber of Heads: ", heads, " [Proportion Heads: ", heads / other$n, "]\n\n", sep = ""))
  }
}