R Scoping/Structural Difficulties

When num =="worst", the function is supposed to be able to retrieve the last row in the data.frame, ha1. However I can't do an if statement like if (num = "worst"), because to get the last row I have to do tail(ha1,1). ha1 is outside the scope of the if statement. Can anyone offer any ways around this? I know there is probably a simple solution I just can't figure it out.

   rankhospital <- function(state,outcome,num)

    {  
      if (num == "best")
  {
    num <- 1

  }


  setwd('C:\\Users\\Admin\\Desktop\\R\\R')
  readFile = read.csv("outcome-of-care-measures.csv", colClasses = "character")

  State = readFile[, "State"]
  Hospital.Name = readFile[, "Hospital.Name"]
  Heart.Attack = readFile[, 11]
  Heart.Failure = readFile[, 17]
  Pneumonia = readFile[, 23]

  #create new Data.Frame with relevant data.
  my.data = data.frame(Heart.Attack, Heart.Failure, Pneumonia, State, Hospital.Name)

  #You need to first identify the state, then read all those entities 
  #into a dataframe of ascending order of mortality for columns,
  #then return the hospital associated with the selected number.

  ha1 <- data.frame(my.data[,1],my.data[,5])
  ha1 <- data.frame(ha1, my.data[4])

  ha1 <- rapply(ha1,as.character,classes = "factor",how  = "replace")


  ha1 <- data.frame(lapply(ha1, as.character), stringsAsFactors=FALSE)
  colnames (ha1)[1] <- "Mortality"
  colnames (ha1)[2] <- "Hospital" 

  ha1[ha1 == "Not Available"] <- NA
  ha1 <- na.omit(ha1)
  ha1 <- ha1[ha1$State == state,]
  rownames(ha1) <- NULL


  if(nrow(ha1) < num){
    stop("NA")
  }


 if(outcome == "pneumonia")
 {
   ha1 <- data.frame(my.data[,2],my.data[,5])
   ha1 <- data.frame(ha1, my.data[4])

   ha1 <- rapply(ha1,as.character,classes = "factor",how  = "replace")


   ha1 <- data.frame(lapply(ha1, as.character), stringsAsFactors=FALSE)
   colnames (ha1)[1] <- "Mortality"
   colnames (ha1)[2] <- "Hospital" 

   ha1[ha1 == "Not Available"] <- NA
   ha1 <- na.omit(ha1)
   ha1 <- ha1[ha1$State == state,]
   rownames(ha1) <- NULL

   if(nrow(ha1) < num){
     stop("NA")
   }


 }

 if(outcome == "heart failure")
 {

   ha1 <- data.frame(my.data[,3],my.data[,5])
   ha1 <- data.frame(ha1, my.data[4])

   ha1 <- rapply(ha1,as.character,classes = "factor",how  = "replace")   
   ha1 <- data.frame(lapply(ha1, as.character), stringsAsFactors=FALSE)
   colnames (ha1)[1] <- "Mortality"
   colnames (ha1)[2] <- "Hospital" 

   ha1[ha1 == "Not Available"] <- NA
   ha1 <- na.omit(ha1)
   ha1 <- ha1[ha1$State == state,]
   rownames(ha1) <- NULL

   if(nrow(ha1) < num){
     stop("NA")
   }

 }
  return(ha1[num,])
}