get_layer_data(), get_layer_grob() now accept integers or characters

Author: lgaborini

R/plot-build.R

@@ -11,13 +11,11 @@
 #' layer. These are useful for tests.
 #'
 #' @param plot ggplot object
-#' @param i An integer. In `get_layer_data()`, the data to return (in the order added to the
+#' @param i An integer or a name of a layer. In `get_layer_data()`, the data to return (in the order added to the
 #'   plot). In `get_layer_grob()`, the grob to return (in the order added to the
-#'   plot). In `get_panel_scales()`, the row of a facet to return scales for.
+#'   plot). In `get_panel_scales()` (only integers allowed), the row of a facet to return scales for.
 #' @param j An integer. In `get_panel_scales()`, the column of a facet to return
 #'   scales for.
-#' @param name A scalar string. In `get_layer_data()` and `get_layer_grob()`, the name of the layer
-#'   to return. If provided and existing, this takes precedence over `i`.
 #' @param ... Not currently in use.
 #' @seealso
 #' [print.ggplot()] and [benchplot()] for
@@ -143,14 +141,14 @@ build_ggplot <- S7::method(ggplot_build, class_ggplot) <- function(plot, ...) {
 
 #' @export
 #' @rdname ggplot_build
-get_layer_data <- function(plot = get_last_plot(), i = 1L, name = NA) {
-  if (is.na(name)) {
-    idx <- i
-  } else {
-    name <- arg_match0(name, names(p@layers))
-    idx <- which(name == names(p@layers))
-  }
-  ggplot_build(plot)@data[[idx]]
+get_layer_data <- function(plot = get_last_plot(), i = 1L) {
+  b <- ggplot_build(plot)
+  idx <- vec_as_location2(
+    i = i,
+    n = vec_size(b@plot@layers),
+    names = names(b@plot@layers)
+  )
+  b@data[[idx]]
 }
 
 #' @export
@@ -177,14 +175,14 @@ layer_scales <- get_panel_scales
 
 #' @export
 #' @rdname ggplot_build
-get_layer_grob <- function(plot = get_last_plot(), i = 1L, name = NA) {
+get_layer_grob <- function(plot = get_last_plot(), i = 1L) {
   b <- ggplot_build(plot)
-  if (is.na(name)) {
-    idx <- i
-  } else {
-    idx <- arg_match0(name, names(p@layers))
-    idx <- which(name == names(p@layers))
-  }
+
+  idx <- vec_as_location2(
+    i = i,
+    n = vec_size(b@plot@layers),
+    names = names(b@plot@layers)
+  )
   b@plot@layers[[idx]]$draw_geom(b@data[[idx]], b@layout)
 }
 

man/ggplot_build.Rd

@@ -147,9 +147,23 @@
 
 # get_layer_data works with layer names
 
-    `name` must be one of "foo" or "bar", not "none".
+    Can't extract elements that don't exist.
+    x Element `none` doesn't exist.
+
+---
+
+    Can't extract elements past the end.
+    i Location 4 doesn't exist.
+    i There are only 2 elements.
 
 # get_layer_grob works with layer names
 
-    `name` must be one of "foo" or "bar", not "none".
+    Can't extract elements that don't exist.
+    x Element `none` doesn't exist.
+
+---
+
+    Can't extract elements past the end.
+    i Location 4 doesn't exist.
+    i There are only 2 elements.
 

tests/testthat/_snaps/layer.md

@@ -231,13 +231,16 @@ test_that("get_layer_data works with layer names", {
 
   # name has higher precedence than index
   expect_identical(
-    get_layer_data(p, i = 1L, name = "bar"),
+    get_layer_data(p, i = "bar"),
     get_layer_data(p, i = 2L)
   )
 
   # name falls back to index
   expect_snapshot_error(
-    get_layer_data(p, i = 1L, name = "none")
+    get_layer_data(p, i ="none")
+  )
+  expect_snapshot_error(
+    get_layer_data(p, i = 4L)
   )
 })
 
@@ -246,13 +249,16 @@ test_that("get_layer_grob works with layer names", {
 
   # name has higher precedence than index
   expect_identical(
-    get_layer_grob(p, i = 1L, name = "bar"),
+    get_layer_grob(p, i = "bar"),
     get_layer_grob(p, i = 2L)
   )
 
   # name falls back to index
   expect_snapshot_error(
-    get_layer_grob(p, i = 1L, name = "none")
+    get_layer_grob(p, i ="none")
+  )
+  expect_snapshot_error(
+    get_layer_grob(p, i = 4L)
   )
 })