Generate secret santa lists

secret_santa.R

# this is taken from Amy Whitehead's great blog: https://amywhiteheadresearch.wordpress.com/2016/12/01/santas-little-helper/

SantasLittleHelper <- function(myFrame,guestList,conflictCols = NULL){
  myTest <- TRUE
  nElves <- 0

  while (myTest == TRUE){
    myOut <- data.frame(gifter = myFrame[,guestList],
                        giftee = sample(myFrame[,guestList],
                                        replace = FALSE,
                                        size=nrow(myFrame))
                        )

    # check that guests haven't drawn themselves
    guestTest<- unlist(lapply(1:nrow(myOut),function(x) {
      myOut$giftee[x] == myFrame[x,guestList]
      }))

    # check for gifting conflicts
    if(!is.null(conflictCols)){

    conflictTest <- unlist(lapply(1:nrow(myOut),function(x) {
      grepl(myOut$giftee[x],myFrame[x,conflictCols])
      }))

    myTest <- any(c(guestTest,conflictTest[!is.na(conflictTest)]))

    } else{
      myTest <- any(guestTest)
    }

    # count the number of iterations needed to avoid conflicts
    nElves <- nElves + 1
  }

  message(paste(nElves,"elves were needed to generate the gift list"))
  return(myOut)
}