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geom_sf does not pass parameters through to layer #2826
Description
Due to this SO question, I discovered that while geom_sf does pass aesthetics through to the appropriate layer (here to plot linestrings as paths), e.g. size, it doesn't pass parameters like lineend, linemitre, linejoin, and arrow, which are parameters of geom_path, not aesthetics like size or linetype. In this case, this makes getting rid of the gaps in this plot harder:
# Reprex from SO question linked above
library(sf)
#> Linking to GEOS 3.6.1, GDAL 2.1.3, proj.4 4.9.3
library(osmdata)
#> Data (c) OpenStreetMap contributors, ODbL 1.0. http://www.openstreetmap.org/copyright
library(ggplot2)
# define bounding box for osm data
my_bbox <- matrix(
c(-0.2605616, -0.2605616,
-0.2004485, -0.2004485,
-0.2605616, 51.4689943,
51.4288980, 51.4288980,
51.4689943, 51.4689943),
ncol = 2
)
bbox_sf <- st_geometry(st_polygon(x = list(my_bbox)))
st_crs(bbox_sf) <- 4326
# get osm road data for bounding box
osm_roads_secondary_sf <-
opq(bbox = st_bbox(bbox_sf)) %>%
add_osm_feature(key = 'highway', value = 'secondary') %>%
osmdata_sf()
ggplot(osm_roads_secondary_sf$osm_lines) +
geom_sf(size = 4, lineend = "round")
#> Warning: Ignoring unknown parameters: lineend
According to ?geom_sf, these parameters get passed through ... to the paired geom/stat or layer, though that function doesn't have parameters for everything or dots—I'm assuming they're passed to its params parameter. The problem here seems to be that the paired stat here is stat_sf, which does not have the specified parameters and is not passing them along further.
Ultimately this behavior is a product of the fact that geom_sf dispatches to so many...geoms? As a sort of meta-geom it's more strongly opinionated than the rest of the API, making it hard to, say, use sf points as locations for geom_text without pulling out the coordinates. Guidance in the docs on what sf geometry type dispatches to what geom (?) (and whether there's a way to override that dispatching) and thus what parameters can be passed would be welcome.
Activity
clauswilke commentedon Aug 13, 2018
The
lineendsetting is hardcoded here:ggplot2/R/sf.R
Line 210 in 5f868c5
To make it configurable, it needs to be made an argument of the
draw_panel()function:ggplot2/R/sf.R
Line 154 in 5f868c5
and then passed through to
sf_grob():ggplot2/R/sf.R
Line 189 in 5f868c5
(and maybe the same should be done for the
linejoinandlinemitreparameters).The
draw_panel()function fromGeomPathcan serve as an example:ggplot2/R/geom-path.r
Lines 143 to 145 in 5f868c5
Do you want to prepare a pull request?
clauswilke commentedon Aug 13, 2018
And if you want to document these parameters and their default settings, you should add them to the constructor function
geom_sf()as well, as can be seen here forgeom_path():ggplot2/R/geom-path.r
Lines 90 to 117 in 5f868c5
alistaire47 commentedon Aug 14, 2018
Ok! It's a busy week, but you've left a good path here, so with a little luck I should be able to get this together relatively quickly.
allow geom_sf to accept line parameters (#2826) (#2847)
lock commentedon Feb 19, 2019
This old issue has been automatically locked. If you believe you have found a related problem, please file a new issue (with reprex) and link to this issue. https://reprex.tidyverse.org/