From abc70e280bf83c1e8cdbe53ba18fdf145d8dd33c Mon Sep 17 00:00:00 2001
From: Teun van den Brand <49372158+teunbrand@users.noreply.github.com>
Date: Thu, 14 Dec 2023 13:21:35 +0100
Subject: [PATCH] `stat_count()` respects uniqueness of `x` (#5520)

* instead of removing, `position_stack()` sets incomplete data to missing

* adjust test

* add test

* Add news bullet
---
 NEWS.md                          |  3 +++
 R/stat-count.R                   |  3 +--
 tests/testthat/test-stat-count.R | 11 +++++++++++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/NEWS.md b/NEWS.md
index dbac0a777b..71f471a2fc 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,8 @@
 # ggplot2 (development version)
 
+* `stat_count()` treats `x` as unique in the same manner `unique()` does 
+  (#4609).
+
 * `position_stack()` no longer silently removes missing data, which is now
   handled by the geom instead of position (#3532).
 
diff --git a/R/stat-count.R b/R/stat-count.R
index 705e0f4226..81790d7aa1 100644
--- a/R/stat-count.R
+++ b/R/stat-count.R
@@ -75,8 +75,7 @@ StatCount <- ggproto("StatCount", Stat,
     x <- data$x
     weight <- data$weight %||% rep(1, length(x))
 
-    count <- as.numeric(tapply(weight, x, sum, na.rm = TRUE))
-    count[is.na(count)] <- 0
+    count <- as.vector(rowsum(weight, x, na.rm = TRUE))
 
     bars <- data_frame0(
       count = count,
diff --git a/tests/testthat/test-stat-count.R b/tests/testthat/test-stat-count.R
index 827ac9f109..7483becf94 100644
--- a/tests/testthat/test-stat-count.R
+++ b/tests/testthat/test-stat-count.R
@@ -4,3 +4,14 @@ test_that("stat_count() checks the aesthetics", {
   p <- ggplot(mtcars) + stat_count(aes(factor(gear), mpg))
   expect_snapshot_error(ggplot_build(p))
 })
+
+test_that("stat_count() respects uniqueness of `x`", {
+  # For #4609, converting x to factor loses smallest digits, so here we test
+  # if they are retained
+  df <- data_frame0(x = c(1, 2, 1, 2) + rep(c(0, 1.01 * .Machine$double.eps), each = 2))
+  p <- ggplot(df, aes(x)) + stat_count(position = "identity")
+  data <- layer_data(p)
+
+  expect_length(vec_unique(df$x), 4)
+  expect_equal(data$y, rep(1, 4))
+})