initial draft

R/derive_vars_cat.R

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+#' Derive pair of variables
+#'
+#'
+#' @param dataset
+#' @param definition
+#'
+#' @return
+#' @export
+#'
+#' @examples
+#'
+#' advs <- tibble::tribble(
+#'   ~USUBJID, ~PARAMCD, ~AVAL,
+#'   "01",     "HEIGHT", 150,
+#'   "02",     "HEIGHT", 135,
+#'   "03",     "HEIGHT", 145
+#' )
+#'
+#' define_tibble <- tribble(
+#'   ~condition,  ~AVALCAT1,  ~AVALCA1N, ~NEWCOL,
+#'   expr(AVAL > 140),  ">140 cm",          1,  "extra1",
+#'   expr(AVAL <= 140), "<=140 cm",         2,  "extra2"
+#' )
+#'
+#'
+#' derive_vars_cat(dataset = advs, definition = define_tibble) %>% print()
+
+derive_vars_cat <- function(dataset,
+                            definition) {
+  # assertions (waiting for feedback first)
+
+  # extract new variable names
+  new_col_names <- names(expr_list)[!names(expr_list)=="condition"]
+
+  # (re)apply the function for each new variable name and iteratively derive the categories
+  new_dataset <- reduce(new_col_names, function(.data, col_name) {
+    # extract conditions
+    condition <- definition[["condition"]] # could also be outside of the function
+    # extract values
+    values <- definition[[col_name]]
+
+    .data %>%
+      mutate(!!sym(col_name) := eval(rlang::call2(
+        "case_when",
+        !!!map2(condition, values, ~ expr(!!.x ~ !!.y))
+      )))
+  }, .init = dataset)
+
+  return(new_dataset)
+}