Utility function to add row names to a data frame

[Mullefa]

Oftentimes, when I am working with a data frame returned from another package, important information will be encoded using the row names of the data frame. Using dplyr, this data should be added as a column (as it is dropped by the manipulation verbs). Something like the following would be useful:

# nse
add_rownames <- function(.data, col_name = "rownames") {
  col_name <- deparse(substitute(col_name))
  add_row_names_(.data, col_name)
}

# se
add_rownames_ <- function(.data, col_name = "rownames") {
  row_names <- data_frame(rownames(.data))
  names(row_names) <- col_name
  dplyr:::cbind_list(row_names, .data)
}

Maybe make the SE version generic?