Computing for data analysis. Week4

agecount.R

agecount <- function(age = NULL) {
  if (is.null(age)){
    stop("age couldn't be NULL")  
  }
  homicides <- readLines("homicides.txt")
  r <- regexec("(\\d+) years old", homicides)
  m <- regmatches(homicides, r)
  causes <- sapply(m, function(x) as.integer(x[2]))
  
  return(length(which(causes==age)))
}

count.R

count <- function(cause = NULL) {
  if (is.null(cause)){
    stop("cause couldn't be NULL")  
  }
  alloved <- c("asphyxiation", "blunt force", "other", "shooting",
               "stabbing", "unknown")
  if (cause %in% alloved) {
    homicides <- readLines("homicides.txt")
    r <- regexec("Cause: ([^<]+)", homicides)
    m <- regmatches(homicides, r)
    causes <- sapply(m, function(x) tolower(x[2]))
    
    return(length(which(causes==cause)))
    
  }
  else {
    stop("cause isn't in the list of alloved")
  }
}