R Programming - Hospital Quality

Summary

The goal of this project is to write function which take hospital data to return the best, worst and ranking number of the hospitals given certain criteria. I wrote one version using for loops and one without using for loops.

rankall <- function(outcome, num = "best") {
      ## Read outcome data
      data <- read.csv("outcome-of-care-measures.csv")
      
      ## Check that outcome is valid
      if (!((outcome == "heart attack") | (outcome == "heart failure")
            | (outcome == "pneumonia"))) {
            stop ("invalid outcome")
      }
      
      ## For each state, find the hospital of the given rank
      col <- if (outcome == "heart attack") {
            11
      } else if (outcome == "heart failure") {
            17
      } else {
            23
      }
      
      data[, col] <- suppressWarnings(as.numeric(levels(data[, col])[data[, col]]))
      data[, 2] <- as.character(data[, 2])
      
      # Generate an empty vector that will be filled later, row by row, to 
      # generate the final output.
      output <- vector()
      
      states <- levels(data[, 7])
      
      for(i in 1:length(states)) {
            statedata <- data[grep(states[i], data$State), ]
            orderdata <- statedata[order(statedata[, col], statedata[, 2], 
                                         na.last = NA), ]
            hospital <- if(num == "best") {
                  orderdata[1, 2]
            } else if(num == "worst") {
                  orderdata[nrow(orderdata), 2]
            } else{
                  orderdata[num, 2]
            }
            output <- append(output, c(hospital, states[i]))
      }
      
      ## Return a data frame with the hospital names and the (abbreviated) 
      ## state name
      output <- as.data.frame(matrix(output, length(states), 2, byrow = TRUE))
      colnames(output) <- c("hospital", "state")
      rownames(output) <- states
      
      output
}