insert a row to a data frame at a wanted position

insertRow.R

insert_row <- function(existingDF, newrow, r){
  r <- as.numeric(r)
  if (length(newrow) != ncol(existingDF)){
    stop("Length of row doesn't match.")
  }
  if (r == 1){
    existingDF <- rbind(newrow,existingDF)
  } else{
    existingDF <- rbind(existingDF[1:(r-1),],newrow,existingDF[-(1:(r-1)),])
  }
  return(existingDF)
}