Fixes #3533 - Swap date(time) types in opposite scale (#6042)

* Fixes #3533 - helpful error msg on date vs datetime scale

* Apply suggestions from code review

Co-authored-by: Thomas Lin Pedersen <[email protected]>

* Apply suggestions from code review

Co-authored-by: Thomas Lin Pedersen <[email protected]>

* add news bullet

* add test

* use internal data.frame

---------
Co-authored-by: Thomas Lin Pedersen <[email protected]>
Co-authored-by: Teun van den Brand <[email protected]>

Author: 3 people

NEWS.md

@@ -1,5 +1,7 @@
 # ggplot2 (development version)
 
+* Date scales silently coerce <POSIXct> to <Date> and datetime scales silently
+  coerce <Date> to <POSIXct> (@laurabrianna, #3533)
 * New parameters for `geom_label()` (@teunbrand and @steveharoz, #5365):
   * The `linewidth` aesthetic is now applied and replaces the `label.size` 
     argument.

R/scale-date.R

@@ -394,6 +394,9 @@ ScaleContinuousDatetime <- ggproto("ScaleContinuousDatetime", ScaleContinuous,
         i = "The value was converted to {obj_type_friendly(x)}."
       ), call = self$call)
     }
+    if (inherits(x, "Date")) {
+      x <- as.POSIXct(x)
+    }
     ggproto_parent(ScaleContinuous, self)$transform(x)
   },
   map = function(self, x, limits = self$get_limits()) {
@@ -441,6 +444,9 @@ ScaleContinuousDate <- ggproto("ScaleContinuousDate", ScaleContinuous,
         i = "The value was converted to {obj_type_friendly(x)}."
       ), call = self$call)
     }
+    if (inherits(x, "POSIXct")) {
+      x <- as.Date(x)
+    }
     ggproto_parent(ScaleContinuous, self)$transform(x)
   },
   get_breaks = function(self, limits = self$get_limits()) {

tests/testthat/test-scale_date.R

@@ -1,4 +1,19 @@
 
+test_that("date(time) scales coerce data types", {
+
+  date     <- as.Date("2024-11-11")
+  datetime <- as.POSIXct(date)
+
+  sc <- scale_x_datetime()
+  df <- sc$transform_df(data_frame0(x = date))
+  expect_equal(df$x, as.numeric(datetime))
+
+  sc <- scale_x_date()
+  df <- sc$transform_df(data_frame0(x = datetime))
+  expect_equal(df$x, as.numeric(date))
+
+})
+
 # Visual tests ------------------------------------------------------------
 
 test_that("date scale draws correctly", {