Fix strips from interactions (#3778)

Author: thomasp85

R/labeller.r

@@ -440,7 +440,7 @@ labeller <- function(..., .rows = NULL, .cols = NULL,
       labellers <- lapply(dots, as_labeller)
     } else {
       margin_labeller <- as_labeller(margin_labeller, default = .default,
-        multi_line = .multi_line)
+                                     multi_line = .multi_line)
 
       # Check that variable-specific labellers do not overlap with
       # margin-wide labeller
@@ -501,29 +501,30 @@ build_strip <- function(label_df, labeller, theme, horizontal) {
   labels <- do.call("cbind", labels)
 
   if (horizontal) {
-    grobs_top <- lapply(labels, element_render, theme = theme,
-                        element = "strip.text.x.top", margin_x = TRUE,
-                        margin_y = TRUE)
+    grobs_top <- apply(labels, c(1, 2), element_render, theme = theme,
+                       element = "strip.text.x.top", margin_x = TRUE,
+                       margin_y = TRUE)
     grobs_top <- assemble_strips(grobs_top, theme, horizontal, clip = "on")
 
-    grobs_bottom <- lapply(labels, element_render, theme = theme,
-                           element = "strip.text.x.bottom", margin_x = TRUE,
-                           margin_y = TRUE)
+    grobs_bottom <- apply(labels, c(1, 2), element_render, theme = theme,
+                          element = "strip.text.x.bottom", margin_x = TRUE,
+                          margin_y = TRUE)
     grobs_bottom <- assemble_strips(grobs_bottom, theme, horizontal, clip = "on")
 
     list(
       top = grobs_top,
       bottom = grobs_bottom
     )
   } else {
-    grobs_left <- lapply(labels, element_render, theme = theme,
-                         element = "strip.text.y.left", margin_x = TRUE,
-                         margin_y = TRUE)
+    grobs_left <- apply(labels, c(1, 2), element_render, theme = theme,
+                        element = "strip.text.y.left", margin_x = TRUE,
+                        margin_y = TRUE)
     grobs_left <- assemble_strips(grobs_left, theme, horizontal, clip = "on")
 
-    grobs_right <- lapply(labels, element_render, theme = theme,
-                          element = "strip.text.y.right", margin_x = TRUE,
-                          margin_y = TRUE)
+    grobs_right <- apply(labels[, rev(seq_len(ncol(labels))), drop = FALSE],
+                         c(1, 2), element_render, theme = theme,
+                         element = "strip.text.y.right", margin_x = TRUE,
+                         margin_y = TRUE)
     grobs_right <- assemble_strips(grobs_right, theme, horizontal, clip = "on")
 
     list(
@@ -549,7 +550,7 @@ assemble_strips <- function(grobs, theme, horizontal = TRUE, clip) {
   if (length(grobs) == 0 || is.zero(grobs[[1]])) return(grobs)
 
   # Add margins to non-titleGrobs so they behave eqivalently
-  grobs <- lapply(grobs, function(g) {
+  grobs[] <- lapply(grobs, function(g) {
     if (inherits(g, "titleGrob")) return(g)
     add_margins(gList(g), grobHeight(g), grobWidth(g), margin_x = TRUE, margin_y = TRUE)
   })
@@ -561,7 +562,7 @@ assemble_strips <- function(grobs, theme, horizontal = TRUE, clip) {
     height <- unit(1, "null")
     width <- max_width(lapply(grobs, function(x) x$widths[2]))
   }
-  grobs <- lapply(grobs, function(x) {
+  grobs[] <- lapply(grobs, function(x) {
     # Avoid unit subset assignment to support R 3.2
     x$widths <- unit.c(x$widths[1], width, x$widths[c(-1, -2)])
     x$heights <- unit.c(x$heights[1], height, x$heights[c(-1, -2)])
@@ -579,10 +580,16 @@ assemble_strips <- function(grobs, theme, horizontal = TRUE, clip) {
   background <- element_render(theme, background)
 
   # Put text on a strip
-  lapply(grobs, function(x) {
-    strip <- ggname("strip", gTree(children = gList(background, x)))
-    strip_table <- gtable(width, height, name = "strip")
-    gtable_add_grob(strip_table, strip, 1, 1, clip = clip)
+  grobs[] <- lapply(grobs, function(x) {
+    ggname("strip", gTree(children = gList(background, x)))
+  })
+  apply(grobs, 1, function(x) {
+    if (horizontal) {
+      mat <- matrix(x, ncol = 1)
+    } else {
+      mat <- matrix(x, nrow = 1)
+    }
+    gtable_matrix("strip", mat, rep(width, ncol(mat)), rep(height, nrow(mat)), clip = clip)
   })
 }