Drop lines in geom_sf() with missing linewidth (#5516)

* Use `non_missing_aes` field in GeomPath

* Add test

* add news bullet

Author: teunbrand

NEWS.md

@@ -1,5 +1,7 @@
 # ggplot2 (development version)
 
+* Lines where `linewidth = NA` are now dropped in `geom_sf()` (#5204).
+
 * New `guide_axis_logticks()` can be used to draw logarithmic tick marks as
   an axis. It supersedes the `annotation_logticks()` function 
   (@teunbrand, #5325).

R/geom-path.R

@@ -132,10 +132,13 @@ GeomPath <- ggproto("GeomPath", Geom,
 
   default_aes = aes(colour = "black", linewidth = 0.5, linetype = 1, alpha = NA),
 
+  non_missing_aes = c("linewidth", "colour", "linetype"),
+
   handle_na = function(self, data, params) {
     # Drop missing values at the start or end of a line - can't drop in the
     # middle since you expect those to be shown by a break in the line
-    complete <- stats::complete.cases(data[names(data) %in% c("x", "y", "linewidth", "colour", "linetype")])
+    aesthetics <- c(self$required_aes, self$non_missing_aes)
+    complete <- stats::complete.cases(data[names(data) %in% aesthetics])
     kept <- stats::ave(complete, data$group, FUN = keep_mid_true)
     data <- data[kept, ]
 

tests/testthat/test-geom-sf.R

@@ -149,6 +149,16 @@ test_that("errors are correctly triggered", {
   expect_snapshot_error(ggplotGrob(p))
   expect_snapshot_error(geom_sf_label(position = "jitter", nudge_x = 0.5))
   expect_snapshot_error(geom_sf_text(position = "jitter", nudge_x = 0.5))
+
+  # #5204: missing linewidth should be dropped
+  pts <- sf::st_sf(
+    geometry = sf::st_sfc(
+      sf::st_linestring(matrix(c(0, 1, 0, 1), ncol = 2)),
+      sf::st_linestring(matrix(c(0, 1, 1, 0), ncol = 2))
+    ),
+    linewidth = c(1, NA)
+  )
+  expect_snapshot_warning(sf_grob(pts, na.rm = FALSE))
 })
 
 # Visual tests ------------------------------------------------------------