R/extract_labels.R

In melidosData: Load Data from the MeLiDos Field Study

#' Extract labels from a list of objects
#'
#' Retrieves the `"label"` attribute from each element in a list and returns
#' a character vector of labels.
#'
#' @param data A list of objects. Each element is expected to have a `"label"`
#'   attribute (e.g., created via `attr(x, "label") <- "some label"`).
#'
#' @returns A character vector containing the `"label"` attribute of each
#'   element in `data`. If an element does not have a `"label"` attribute,
#'   `NA_character_` is returned for that element.
#'
#' @export
#'
#' @examples
#' # Create example data with labels
#' x1 <- 1:3
#' attr(x1, "label") <- "First variable"
#'
#' x2 <- 4:6
#' attr(x2, "label") <- "Second variable"
#'
#' x3 <- 7:9
#' # No label set for x3
#'
#' data <- list(x1, x2, x3)
#'
#' # Extract labels
#' extract_labels(data)
#'
#' # Works for data frames as well
#' data <- data.frame (x1, x2, x3)
#' extract_labels(data)
extract_labels <- function(data){
  purrr::map_chr(data, \(x) attr(x,"label") %||% NA_character_ )
}