Speedups for epix_slide

R/grouped_epi_archive.R

@@ -186,6 +186,7 @@ grouped_epi_archive =
 #'   object. See the documentation for the wrapper function [`epix_slide()`] for
 #'   details.
 #' @importFrom data.table key address rbindlist
+#' @importFrom tibble as_tibble
 #' @importFrom rlang !! !!! enquo quo_is_missing enquos is_quosure sym syms
 #'  env missing_arg
           slide = function(f, ..., before, ref_time_values,
@@ -280,16 +281,18 @@ grouped_epi_archive =
               if (! (is.atomic(comp_value) || is.data.frame(comp_value))) {
                 Abort("The slide computation must return an atomic vector or a data frame.")
               }
+              # Convert from data.frame to tibble for speed.
+              # Label every result row with the `ref_time_value`
+              res <- as_tibble(data.frame(time_value = ref_time_value))
+
               # Wrap the computation output in a list and unchop/unnest later if
               # `as_list_col = FALSE`. This approach means that we will get a
               # list-class col rather than a data.frame-class col when
               # `as_list_col = TRUE` and the computations outputs are data
               # frames.
-              comp_value <- list(comp_value)
+              res[[new_col]] <- list(comp_value)
 
-              # Label every result row with the `ref_time_value`:
-              return(tibble::tibble(time_value = .env$ref_time_value,
-                                    !!new_col := .env$comp_value))
+              return(res)
             }
 
             # If `f` is missing, interpret ... as an expression for tidy evaluation