Bug fix: allow empty Vlines and Hlines as ggplot2 does

NEWS.md

@@ -12,6 +12,7 @@
 * Closed #2208: `ggplotly()` no longer errors given a `geom_area()` with 1 or less data points (error introduced by new behavior in ggplot2 v3.4.0). (#2209)
 * Closed #2220: `ggplotly()` no longer errors on `stat_summary(geom = "crossbar")`. (#2222)
 * Closed #2212: `ggplotly()` no longer removes legends when setting guide properties via `guides(aes = guide_xxx(...))`.
+* Closed #1947: `ggplotly()` now correctly handles `geom_vline`/`geom_hline` with empty data. Previously, if `geom_vline`/`geom_hline` was passed an empty data frame, it would result in an error. The plot is drawn even if no lines are found; this is the same behavior as `ggplot2`.
 
 # 4.10.1
 

R/layers2traces.R

@@ -445,7 +445,9 @@ to_basic.GeomHline <- function(data, prestats_data, layout, params, p, ...) {
     data = layout$layout, cols = paste0(x, c("_min", "_max")), values_to = x, names_to = "variable"
   ) 
   lay <- as.data.frame(lay)
-  data <- merge(lay[c("PANEL", x)], data, by = "PANEL")
+  if (nrow(data) > 0) {
+    data <- merge(lay[c("PANEL", x)], data, by = "PANEL")
+  }
   data[["x"]] <- data[[x]]
   data[["y"]] <- data$yintercept
   prefix_class(data, c("GeomHline", "GeomPath"))
@@ -462,7 +464,9 @@ to_basic.GeomVline <- function(data, prestats_data, layout, params, p, ...) {
     data = layout$layout, cols = paste0(y, c("_min", "_max")), values_to = y, names_to = "variable"
   ) 
   lay <- as.data.frame(lay)
-  data <- merge(lay[c("PANEL", y)], data, by = "PANEL")
+  if (nrow(data) > 0) {
+    data <- merge(lay[c("PANEL", y)], data, by = "PANEL")
+  }
   data[["y"]] <- data[[y]]
   data[["x"]] <- data$xintercept
   prefix_class(data, c("GeomVline", "GeomPath"))

tests/testthat/test-ggplot-hline.R

@@ -97,3 +97,8 @@ test_that("hline works with coord_flip", {
   expect_equivalent(l$data[[2]]$x, c(5, 5))
   expect_equivalent(l$data[[2]]$y, c(5.95, 6.05))
 })
+
+test_that("geom_vline/geom_hline does not throw an error with ggplotly when no lines are found", {
+  p3 <- ggplot(df) + geom_hline(aes(yintercept = x), data = data.frame(x = 1)[F, , drop = FALSE])
+  expect_error(plotly::ggplotly(p3), NA)
+})

tests/testthat/test-ggplot-vline.R

@@ -46,3 +46,8 @@ test_that("vline works with coord_flip", {
   expect_equivalent(l$data[[2]]$x, c(5.95, 6.05))
   expect_equivalent(l$data[[2]]$y, c(5, 5))
 })
+
+test_that("geom_vline/geom_hline does not throw an error with ggplotly when no lines are found", {
+  p <- ggplot(df) + geom_vline(aes(xintercept = x), data = data.frame(x = 1)[F, , drop = FALSE])
+  expect_error(plotly::ggplotly(p), NA)
+})