Programming assignment 3 for Coursera "R Programming" course by Johns Hopkins University

best.R

best <- function(state, outcome) {
  ## Read outcome data
  ## Check that state and outcome are valid
  ## Return hospital name in that state with lowest 30-day death
  ## rate
  
  source("sortHospitalsByOutcome.R")
  head(sortHospitalsByOutcome(state, outcome), 1)
}

outcomeCol.R

outcomeCol <- function(outcome) {
  if (outcome == "heart attack") {
    outcome <- "Hospital.30.Day.Death..Mortality..Rates.from.Heart.Attack"
  } else if (outcome == "heart failure") {
    outcome <- "Hospital.30.Day.Death..Mortality..Rates.from.Heart.Failure"
  } else if (outcome == "pneumonia") {
    outcome <- "Hospital.30.Day.Death..Mortality..Rates.from.Pneumonia"
  }
  else {
    stop("invalid outcome")
  }
}

rankall.R

rankall <- function(outcome, num="best") {
  ## Read outcome data
  ## Check that state and outcome are valid
  ## For each state, find the hospital of the given rank
  ## Return a data frame with the hospital names and the
  ## (abbreviated) state name
  
  source("outcomeCol.R")
  
  outcome <- outcomeCol(outcome)
  
  data <- read.csv("data/outcome-of-care-measures.csv",  colClasses="character")
  data[,outcome] <- suppressWarnings(as.numeric(data[,outcome]))
  data <- data[order(data$"State", data[outcome], data$"Hospital.Name", na.last=NA),]
  data <- data[!is.na(outcome)]
  
  l <- split(data[,c("Hospital.Name")], data$State)

  rankHospitals <- function(x, num) {
    if (num=="best") {
      head(x, 1)
    } else if (num=="worst") {
      tail(x, 1)
    } else {
      x[num]
    }
  }

  result <- lapply(l, rankHospitals, num)
  data.frame(hospital = unlist(result), state = names(result), row.names = names(result))
}

rankhospital.R

rankhospital <- function(state, outcome, num = "best") {
  ## Read outcome data
  ## Check that state and outcome are valid
  ## Return hospital name in that state with the given rank
  ## 30-day death rate
  
  source("best.R")
  source("sortHospitalsByOutcome.R")
  
  if (num=="best") {
    best(state, outcome)
  } else if (num=="worst") {
    tail(sortHospitalsByOutcome(state, outcome), 1)
  } else {
    sortHospitalsByOutcome(state, outcome)[num]
  }
}

sortHospitalsByOutcome.R

sortHospitalsByOutcome <- function(state, outcome) {
  source("outcomeCol.R")
  outcome <- outcomeCol(outcome)
  
  data <- read.csv("data/outcome-of-care-measures.csv", stringsAsFactors=FALSE)
  
  if (!state %in% data$State) {
    stop("invalid state")
  }
  
  data <- data[data$State==state,]
  
  data[,outcome] <- suppressWarnings(as.numeric(data[,outcome]))
  data <- data[order(data[outcome], data$"Hospital.Name"),]
  as.character(data$"Hospital.Name"[!is.na(data[outcome])])
}

Good one but calling functions in other codes makes it difficult plus time consuming!