handle factors correctly

Author: clauswilke

R/sf.R

@@ -457,13 +457,14 @@ CoordSf <- ggproto("CoordSf", CoordCartesian,
         x_labels <- scale_x$labels
       }
 
-      if (is.character(x_labels)) {
+      # all labels need to be temporarily stored as character vectors,
+      # but expressions need to be parsed afterwards
+      if (is.character(x_labels) || is.factor(x_labels)) {
         needs_parsing[graticule$type == "E"] <- FALSE
       } else {
-        # all labels need to be temporarily stored as character vectors
-        x_labels <- as.character(x_labels)
         needs_parsing[graticule$type == "E"] <- TRUE
       }
+      x_labels <- as.character(x_labels)
     }
 
     if (length(x_labels) != length(x_breaks)) {
@@ -485,13 +486,14 @@ CoordSf <- ggproto("CoordSf", CoordCartesian,
         y_labels <- scale_y$labels
       }
 
-      if (is.character(y_labels)) {
+      # all labels need to be temporarily stored as character vectors,
+      # but expressions need to be parsed afterwards
+      if (is.character(y_labels) || is.factor(y_labels)) {
         needs_parsing[graticule$type == "N"] <- FALSE
       } else {
-        # all labels need to be temporarily stored as character vectors
-        y_labels <- as.character(y_labels)
         needs_parsing[graticule$type == "N"] <- TRUE
       }
+      y_labels <- as.character(y_labels)
     }
     if (length(y_labels) != length(y_breaks)) {
       stop("Breaks and labels along y direction are different lengths", call. = FALSE)

tests/testthat/test-coord_sf.R

@@ -60,6 +60,30 @@ test_that("axis labels can be set manually", {
     c("D", "E", "F")
   )
 
+  # factors are treated like character labels
+  # and are not parsed
+  b <- ggplot_build(
+    plot +
+      scale_x_continuous(
+        breaks = c(1000, 2000, 3000),
+        labels = factor(c("A", "B", "C"))
+      ) +
+      scale_y_continuous(
+        breaks = c(1000, 1500, 2000),
+        labels = factor(c("1 * degree * N", "1.5 * degree * N", "2 * degree * N"))
+      )
+  )
+  graticule <- b$layout$panel_params[[1]]$graticule
+  expect_identical(
+    graticule[graticule$type == "E", ]$degree_label,
+    c("A", "B", "C")
+  )
+  expect_identical(
+    graticule[graticule$type == "N", ]$degree_label,
+    c("1 * degree * N", "1.5 * degree * N", "2 * degree * N")
+  )
+
+
   # expressions mixed with character labels
   b <- ggplot_build(
     plot +