Get rankings for US hospitals for a given state

rankhospital.R

rankhospital <- function(state, outcome, num = "best") {
   dissease <- c("heart attack", "heart failure", "pneumonia")
   ## Read data
   dataset <- read.csv("outcome-of-care-measures.csv",
                       colClasses = "character")
   dataset[, 11] <- suppressWarnings ( as.numeric(dataset[, 11]) )
   dataset[, 17] <- suppressWarnings ( as.numeric(dataset[, 17]) )
   dataset[, 23] <- suppressWarnings ( as.numeric(dataset[, 23]) )
   ## Check that state and outcome are valid
   if(!is.element(outcome, dissease)){
      stop("invalid outcome")
   }
   if(!state %in% unique(dataset[!is.na(dataset$State), c("State")]) ){
      stop("invalid state")
   }
   ## Return hospital name in that state
   ## with lowest 30-day death rate
   if (identical(outcome,dissease[1])) {
      scolumn <- 11
   }
   else if (identical(outcome,dissease[2])) {
      scolumn <- 17
   }
   else {
      scolumn <- 23
   }
   data <- dataset[
      which(!is.na(dataset[, scolumn])
            & dataset$State %in% state),
      ]
   if (num == "best") {
      result <- head( data[ order(data[,scolumn],
                                  data[,2]), c("Hospital.Name")] , n = 1)
      result
   } else if (num == "worst") {
      result <- tail( data[ order(data[,scolumn],
                                  data[,2]), c("Hospital.Name")] , n = 1)
      result
   } else {
      result <- data[ order(data[,scolumn],
                            data[,2]), c("Hospital.Name")]
      tryCatch({ result[num] }, error = function (e) {NA} )
   }
}