From d9294c89b4bfef8a8259efaaed73498739e4c7e9 Mon Sep 17 00:00:00 2001
From: Hiroaki Yutani <yutani.ini@gmail.com>
Date: Mon, 1 Jul 2024 10:45:04 +0900
Subject: [PATCH 1/2] Expose position arg on geom_hline() and geom_vline()

---
 R/geom-hline.R     |  3 ++-
 R/geom-vline.R     |  3 ++-
 man/geom_abline.Rd | 15 +++++++++++++++
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/R/geom-hline.R b/R/geom-hline.R
index 924b41f40a..6b80d0bb08 100644
--- a/R/geom-hline.R
+++ b/R/geom-hline.R
@@ -4,6 +4,7 @@ NULL
 #' @export
 #' @rdname geom_abline
 geom_hline <- function(mapping = NULL, data = NULL,
+                       position = "identity",
                        ...,
                        yintercept,
                        na.rm = FALSE,
@@ -29,7 +30,7 @@ geom_hline <- function(mapping = NULL, data = NULL,
     mapping = mapping,
     stat = StatIdentity,
     geom = GeomHline,
-    position = PositionIdentity,
+    position = position,
     show.legend = show.legend,
     inherit.aes = FALSE,
     params = list2(
diff --git a/R/geom-vline.R b/R/geom-vline.R
index 2705093f05..85cacf3e63 100644
--- a/R/geom-vline.R
+++ b/R/geom-vline.R
@@ -4,6 +4,7 @@ NULL
 #' @export
 #' @rdname geom_abline
 geom_vline <- function(mapping = NULL, data = NULL,
+                       position = "identity",
                        ...,
                        xintercept,
                        na.rm = FALSE,
@@ -29,7 +30,7 @@ geom_vline <- function(mapping = NULL, data = NULL,
     mapping = mapping,
     stat = StatIdentity,
     geom = GeomVline,
-    position = PositionIdentity,
+    position = position,
     show.legend = show.legend,
     inherit.aes = FALSE,
     params = list2(
diff --git a/man/geom_abline.Rd b/man/geom_abline.Rd
index 9e13bc3de8..8fd63ae8e0 100644
--- a/man/geom_abline.Rd
+++ b/man/geom_abline.Rd
@@ -19,6 +19,7 @@ geom_abline(
 geom_hline(
   mapping = NULL,
   data = NULL,
+  position = "identity",
   ...,
   yintercept,
   na.rm = FALSE,
@@ -28,6 +29,7 @@ geom_hline(
 geom_vline(
   mapping = NULL,
   data = NULL,
+  position = "identity",
   ...,
   xintercept,
   na.rm = FALSE,
@@ -89,6 +91,19 @@ a warning. If \code{TRUE}, missing values are silently removed.}
 It can also be a named logical vector to finely select the aesthetics to
 display.}
 
+\item{position}{A position adjustment to use on the data for this layer. This
+can be used in various ways, including to prevent overplotting and
+improving the display. The \code{position} argument accepts the following:
+\itemize{
+\item The result of calling a position function, such as \code{position_jitter()}.
+This method allows for passing extra arguments to the position.
+\item A string naming the position adjustment. To give the position as a
+string, strip the function name of the \code{position_} prefix. For example,
+to use \code{position_jitter()}, give the position as \code{"jitter"}.
+\item For more information and other ways to specify the position, see the
+\link[=layer_positions]{layer position} documentation.
+}}
+
 \item{xintercept, yintercept, slope, intercept}{Parameters that control the
 position of the line. If these are set, \code{data}, \code{mapping} and
 \code{show.legend} are overridden.}

From ea8a5dd11514464a922f3e7e3bce19fc45852296 Mon Sep 17 00:00:00 2001
From: Hiroaki Yutani <yutani.ini@gmail.com>
Date: Mon, 1 Jul 2024 16:46:30 +0900
Subject: [PATCH 2/2] Add a NEWS bullet [skip ci]

---
 NEWS.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/NEWS.md b/NEWS.md
index d553c7f924..f739f2b4a0 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -99,6 +99,8 @@
   the `nbin` argument (@teunbrand, #5882, #5036)
 * `after_stat()` and `after_scale()` throw warnings when the computed aesthetics
   are not of the correct length (#5901).
+* `geom_hline()` and `geom_vline()` now have `position` argument
+  (@yutannihilation, #4285).
 
 # ggplot2 3.5.1