type_text() retains categorical axes

NEWS.md

@@ -214,6 +214,8 @@ related to plot layering. See "Bug fixes" below.
 
 ### Bug fixes
 
+- `type_text()` no longer converts a categorical axis to a numeric one.
+  (#730 @grantmcdermott)
 - Fixed a bug where consecutive plots with (i) logged axes under (ii) a dynamic
   theme would error, due to a stale `par("xlog")`/`par("ylog")` state. We now
   avoid this by grabbing the log state directly from the top-level `log`

R/type_text.R

@@ -166,14 +166,26 @@ data_text = function(labels = NULL, labeller = NULL, clim = c(0.5, 2.5)) {
       labels = tinylabel(labels, labeller)
     }
     datapoints$labels = labels
+    # Collapse a categorical axis to its level positions, keeping the levels as
+    # the axis labels. (#730)
     if (is.factor(datapoints$x)) {
-      datapoints$x = as.numeric(datapoints$x)
+      xlvls = levels(datapoints$x)
+      xlabs = seq_along(xlvls)
+      names(xlabs) = xlvls
+      datapoints$x = as.integer(datapoints$x)
+    } else {
+      xlabs = NULL
     }
     if (is.factor(datapoints$y)) {
-      datapoints$y = as.numeric(datapoints$y)
+      ylvls = levels(datapoints$y)
+      ylabs = seq_along(ylvls)
+      names(ylabs) = ylvls
+      datapoints$y = as.integer(datapoints$y)
+    } else {
+      ylabs = NULL
     }
 
-    env2env(environment(), settings, "datapoints")
+    env2env(environment(), settings, c("datapoints", "xlabs", "ylabs"))
   }
   return(fun)
 }

inst/tinytest/test-type_text.R

@@ -71,3 +71,9 @@ expect_snapshot_plot(f, label = "text_labels_nse")
 expect_error(tinyplot(mpg ~ wt, data = mtcars, type = "text", labels = c("a", "b")))
 # top-level `labels` overrides the constructor-level arg
 expect_silent(tinyplot(1:3, type = type_text(labels = "x"), labels = c("a", "b", "c")))
+
+# A categorical axis stays categorical (#730)
+f = function() {
+  tinyplot(x = LETTERS[1:2], y = 1:2, type = "text")
+}
+expect_snapshot_plot(f, label = "text_categorical_x")