rankall.R

## R Programming Assignment 3 - Part III

## TASKS: 
## (1)  Plot the 30-day mortality rates for heart attack
## (2)  Finding the best hospital in a state
## (3)  Ranking hospitals by outcome in a state
## -> (4)  Ranking hospitals in all states


## (4)  Ranking hospitals in all states

rankall <- function (outcome_name, num = "best") {
        
        setwd("/Users/lucky1eva/Downloads/rprog-data-ProgAssignment3-data/")
        outcome <- read.csv("outcome-of-care-measures.csv") 
        
        # Check validity
        if (!outcome_name %in% c("heart attack", "heart failure", "pneumonia")) {
                
                stop("invalid outcome")
                
        }
        
        # Subset relevant data from all states 
        outcome <- subset(outcome, select = c("Hospital.Name","State", 
                                                "Hospital.30.Day.Death..Mortality..Rates.from.Heart.Attack", 
                                                "Hospital.30.Day.Death..Mortality..Rates.from.Heart.Failure",
                                                "Hospital.30.Day.Death..Mortality..Rates.from.Pneumonia"))
        
        # Assign colnames to match the arguments in terms of outcome_name
        colnames(outcome) <- c("Name","State", "heart attack", "heart failure", "pneumonia")
        
        # Correct classes of each variable
        outcome[, 3:5] <- apply(outcome[, 3:5], 2, function(x) as.numeric(x))
        outcome[, 1:2] <- apply(outcome[, 1:2], 2, function(x) as.character(x))
        
        # Restructure the data frame and keep the class unchanged
        outcome_by_state <- split(outcome, outcome$State)   # split outcome table by state
        outcome_table <- lapply(outcome_by_state, as.data.frame) # set each element class to data.frame
        
        # define a function to use lapply() to set new order for each table at once
        f <- function (x, y) {x[order(x[, y], x[, 1]), ]}
       
        sorted_table <- lapply(outcome_table, f, y = outcome_name)
        
        all_listed <- NULL # just to define the return variable used in the following
        
        for (i in 1:54) { # check in each state if the rank requested by 'num' is numeric / char and if within range
                
                if (class(num) == "numeric" && num <= sum(!is.na(sorted_table[[i]][, outcome_name])) && num >= 1) {
                             
                        all_listed <- rbind(all_listed, sorted_table[[i]][num, 1:2])                
                                    
                } else if (class(num) == "numeric" && num > sum(!is.na(sorted_table[[i]][, outcome_name])) ) { 
                                
                        all_listed <- rbind(all_listed, data.frame("Name" = NA, "State" = names(sorted_table[i])))
                               
                } else if ( num == "best") {
                                
                        all_listed <- rbind(all_listed, sorted_table[[i]][1, 1:2])  
                        
                } else if (num == "worst") {
                        
                        all_listed <- rbind(all_listed, sorted_table[[i]][sum(!is.na(sorted_table[[i]][, outcome_name])), 1:2])          
                        
                        }
        }
                
          
        all_listed     
        
}