ch05-coding-style.R

# 지저분한 코드 예
sc<-function(x,y,verbose=TRUE) {
n<-length(x)
if(n<=1||n!=length(y)) stop("Arguments x and y have different lengths: ",length(x)," and ",length(y),".")
if(TRUE%in%is.na(x)||TRUE%in%is.na(y)) stop(" Arguments x and y must not have missing values.")
cv<-var(x,y)
if(verbose) cat("Covariance = ",round(cv,4),".\n",sep= "")
return(cv)
}



# 깨끗한 코드 예
CalculateSampleCovariance <- function(x, y, verbose = TRUE) {
  # Computes the sample covariance between two vectors.
  #
  # Args:
  #   x: One of two vectors whose sample covariance is to be calculated.
  #   y: The other vector. x and y must have the same length, greater than one,
  #      with no missing values.
  #   verbose: If TRUE, prints sample covariance; if not, not. Default is TRUE.
  #
  # Returns:
  #   The sample covariance between x and y.
  n <- length(x)
  # Error handling
  if (n <= 1 || n != length(y)) {
    stop("Arguments x and y have different lengths: ",
         length(x), " and ", length(y), ".")
  }
  if (TRUE %in% is.na(x) || TRUE %in% is.na(y)) {
    stop(" Arguments x and y must not have missing values.")
  }
  covariance <- var(x, y)
  if (verbose)
    cat("Covariance = ", round(covariance, 4), ".\n", sep = "")
  return(covariance)
}