add explanation for handling additional keys

Author: mgyliu

R/epi_df.R

@@ -105,8 +105,9 @@ NULL
 #'   then the current day-time will be used.
 #' @param additional_metadata List of additional metadata to attach to the
 #'   `epi_df` object. The metadata will have `geo_type`, `time_type`, and
-#'   `as_of` fields; named entries from the passed list or will be included as
-#'   well.
+#'   `as_of` fields; named entries from the passed list will be included as
+#'   well. If your tibble has additional keys, be sure to specify them 
+#'   in the `other_keys` component of `additional_metadata`. 
 #' @param ... Additional arguments passed to methods.
 #' @return An `epi_df` object.
 #' 
@@ -188,8 +189,9 @@ new_epi_df = function(x = tibble::tibble(), geo_type, time_type, as_of,
 #'   then the current day-time will be used.
 #' @param additional_metadata List of additional metadata to attach to the
 #'   `epi_df` object. The metadata will have `geo_type`, `time_type`, and
-#'   `as_of` fields; named entries from the passed list or will be included as
-#'   well.
+#'   `as_of` fields; named entries from the passed list will be included as
+#'   well. If your tibble has additional keys, be sure to specify them 
+#'   in the `other_keys` component of `additional_metadata`.
 #' @param ... Additional arguments passed to methods.
 #' @return An `epi_df` object.
 #'
@@ -248,9 +250,12 @@ new_epi_df = function(x = tibble::tibble(), geo_type, time_type, as_of,
 #' 
 #' ex3 <- ex3_input %>% 
 #'   tsibble::as_tsibble() %>% # needed to add the additional metadata
+#'   # add 2 extra keys
 #'   dplyr::mutate(
 #'     state = rep("MA",6),
-#'     pol = rep(c("blue", "swing", "swing"), each = 2)) %>% # 2 extra keys
+#'     pol = rep(c("blue", "swing", "swing"), each = 2)) %>% 
+#'   # the 2 extra keys we added have to be specified in the other_keys 
+#'   # component of additional_metadata.
 #'   as_epi_df(additional_metadata = list(other_keys = c("state", "pol")))
 #' 
 #' attr(ex3,"metadata")