R/flatten_dataframe_prime.R

In UBC-MDS/mlist_R: mlist

#' Flattens a list so that all prime numbers in embedded lists are 
#' returned in a flat list
#' 
#' @param df A dataframe of numbers; largest number cannot be greater than 1000
#' @return A numeric vector that has all of the prime numbers in df
#' 
#' @export
#' @examples
#' a <- data.frame(c(2, 3, 4), c(5, 6, 7), c(8, 9, 10))
#' flatten_dataframe_prime(a)
#' # returns the numeric vector c(2, 3, 5, 7)
#' 
flatten_dataframe_prime <- function(df) {
  LIMIT <- 1000
  
  # check for type of input
  if (!is.data.frame(df)) {
    stop("Input is not a dataframe")
  }
  
  prime <- c(2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,
           89,97,101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,
           181,191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,
           277,281,283,293,307,311,313,317,331,337,347,349,353,359,367,373,379,
           383,389,397,401,409,419,421,431,433,439,443,449,457,461,463,467,479,
           487,491,499,503,509,521,523,541,547,557,563,569,571,577,587,593,599,
           601,607,613,617,619,631,641,643,647,653,659,661,673,677,683,691,701,
           709,719,727,733,739,743,751,757,761,769,773,787,797,809,811,821,823,
           827,829,839,853,857,859,863,877,881,883,887,907,911,919,929,937,941,
           947,953,967,971,977,983,991,997)
  primes_in_df <- c()
  for (row_ind in 1:nrow(df)) {
    for (col_ind in 1:ncol(df)) {
      # to make a df w/o cols or rows: data.frame()
      # check that all elements in the dataframe are numeric
      
      if (!is.numeric(df[row_ind, col_ind])) {
        print(df[row_ind, col_ind])
        stop(paste("All elements in the dataframe must be numeric.  Non-numeric element at row", 
                   row_ind, "col", col_ind))
      }
      
      # check that the number is less than or equal the largeset allowed number
      if (df[row_ind, col_ind] > LIMIT) {
        stop(paste("All numbers in the dataframe must be less than", LIMIT, 
                   "Invalid number at row", row_ind, "col", col_ind))
      }
      
      if ((df[row_ind, col_ind] %in% prime) && !(df[row_ind, col_ind] %in% primes_in_df)) {
        primes_in_df <- append(primes_in_df, df[row_ind, col_ind])
      }
    }
  }
  return(sort(primes_in_df))
}