R/exists_straight.R

In dfcorbin/pokersim:

#' Determine if a straight exists.
#'
#'
#' @param cards  A list of objects from the S4 Class 'card'.
#'
#' @return A list containing a logical representing if there is a flush,
#' and the straight itself if there is one.
#' @export
#'
#' @examples
exists_straight <- function(cards){
  n <- length(cards)
  #Retreive the vector of values from the cards.
  values <- c()
  for ( i in 1:n){
    values <- c(values,cards[[i]]@value)
  }

  #add the original indexes as names so we can keep
  #track of which value relates to which card.
  names(values) <- paste(1:n)
  values <- sort(values,decreasing = TRUE)

  #We will account for the case where an ace can
  #be used as both 1 and 14.
  if (1 %in% values){
    values <- c(14,values) #Assign the same name
    #to the duplicate ace so correct card returned.
    names(values)[1] <- names(values[n+1])
  }

  unique_vals <- values %>% unique()
  #Find the values which make up the straight
  for(i in 1:(n-4)){
    check <- unique_vals[i:(i+4)]
    compare <- unique_vals[i]:(unique_vals[i]-4)
    if (setequal(check,compare)){
      #Retrieve the indexes from values
      index <- match(check,values)
      #Retrieve the original index relating to which card to use.
      index <- names(values[index])
      return(list("logical" = TRUE,"cards" = cards[as.numeric(index)]))
    }
  }
  return(list("logical" = FALSE))
}

set.seed(102)
cards <- new_cards(15,new_deck())[-16]
cards <- exists_straight(cards)