guide_axis_theta: fix missing label for one unique key

Author: Yunuuuu

R/guide-axis-theta.R

@@ -104,8 +104,9 @@ GuideAxisTheta <- ggproto(
 
       # If the first and last positions are close together, we merge the
       # labels of these positions
-      ends_apart <- (key$theta[n] - key$theta[1]) %% (2 * pi)
-      if (n > 0 && ends_apart < 0.05 && !is.null(key$.label)) {
+      if (n > 1L &&
+        (key$theta[n] - key$theta[1]) %% (2 * pi) < 0.05 &&
+        !is.null(key$.label)) {
         if (is.expression(key$.label[[1]])) {
           combined <- substitute(
             paste(a, "/", b),

tests/testthat/_snaps/guide-axis/guide-axis-theta-with-only-one-axis-value.svg

@@ -382,6 +382,14 @@ test_that("guide_axis_theta sets relative angle", {
   expect_doppelganger("guide_axis_theta with angle adapting to theta", p)
 })
 
+test_that("guide_axis_theta with only one axis value", {
+  p <- ggplot(data.frame(x = "a", y = 1:3), aes(x, y)) +
+    geom_point() +
+    coord_radial(start = 0, end = pi / 2, inner.radius = 0.5) +
+    guides(theta = guide_axis_theta(angle = 0))
+  expect_doppelganger("guide_axis_theta with only one axis value", p)
+})
+
 test_that("guide_axis_theta can be used in cartesian coordinates", {
 
   p <- ggplot(mtcars, aes(disp, mpg)) +