removing duplicate entries across rows and columns

remove_duplicate_rows_columns.R

ex_data = data.frame(A = c("A", "C", "E", "F", "G", "H", "I"),
                     B = c("B", "D", "A", "E", "I", "J", "K"),
                     C = "C",
                     stringsAsFactors = FALSE)

irow = 2
consider_cols = c("A", "B")
all_entries = unlist(ex_data[1, consider_cols], use.names = FALSE)
while (irow <= nrow(ex_data)) {
  message(c(irow, nrow(ex_data)))
  new_entries = unlist(ex_data[irow, consider_cols], use.names = FALSE)
  if (any(new_entries %in% all_entries)) {
    ex_data = ex_data[-irow, ]
  } else {
    all_entries = c(all_entries, new_entries)
    irow = irow + 1
  }
}

print(ex_data)

So we start by saving all_entries is the first row, and we unlist it because it is a data.frame and really we just want the entries.

Then, while irow is less than the total rows (so this will go until the end, no matter how big, I think), we get the next rows entries, and check if any were in all the entries thus far. If yes, get rid of that row, and don't update the row incrementer, if no, add the entries to all, and then increment the counter to go to the next row.