What I'm trying to do: plot spatial objects with ggspatial::geom_sf(), using coord_sf() or a combination of ggspatial::layer_spatial() and ggspatial::annotation_spatial() to specify the extent of the of the plot.
This ggplot/ggspatial behavior has been described in several posts, but the "solutions" have been just ad-hoc hacks that do nothing to ensure the issue doesn't re-occur. See: Setting limits for x and y using coord_sf after updating ggplot2 Error when plotting latitude and longitude points on US map in RStudio
This code works just fine:
require(sf); require(ggspatial); require(rnaturalearth)
country_polygons <- st_as_sf(ne_countries())
ggplot() + geom_sf(data=country_polygons)
As does this:
ggplot() + geom_sf(data=country_polygons) + coord_sf(xlim=c(-100,100), ylim=c(-60,60))
But:
ggplot() + geom_sf(data=country_polygons) + coord_sf(xlim=c(-160,150), ylim=c(-60,60))
Results in the error: Error in st_cast.POINT(X[[i]], ...) : cannot create MULTILINESTRING from POINT
Obviously this should not be happening. I don't understand why geom_sf calls st_cast.POINT() since there should be no points in the input. I've tried with three different world maps (the GADM 3.6 shapefile, rworldmap::countriesLow and the rnaturalearth one), so it doesn't seem to be dataset specific.
Using these x and y limits values, even a simple sf point object fails to plot!
set.seed(80085)
tibble(Lon=runif(1000,-180,180),
Lat=runif(1000,-90,90)) %>%
st_as_sf(coords=1:2, remove=F, crs=4326) -> random_points
random_points %>%
ggplot() + geom_sf() + coord_sf(xlim=c(-160,150), ylim=c(-60,60))
The error message is again "cannot create MULTILINESTRING from POINT" which I have no idea why it would try to create a MULTILINESTRING.
UPDATE: The solution suggested here doesn't work: Why do some xlims and ylims produce this error in ggplot and sf?
random_points %>%
st_crop(xmin=-160, xmax=150, ymin=-60, ymax=60) %>%
ggplot() + geom_sf()
Results, weirdly, in only the points between 150oE and 160oW, i.e. over the Pacific Ocean around the 180th longitude, being preserved. I tried using longitudes from 0 to 360 and swapping the xmin and xmax, to no avail.
Faulty behavior of st_crop aside, passing a correct cropped object gives the same error again:
random_points %>%
filter(Lon<150, Lon>-160, Lat>-60, Lat<60) %>%
ggplot() + geom_sf()
> Error in st_cast.POINT(x[[1]], to, ...) :
cannot create MULTILINESTRING from POINT
In addition: Warning message:
In st_cast.GEOMETRYCOLLECTION(X[[i]], ...) :
only first part of geometrycollection is retained
END UPDATE
Is there a solution or a workaround?
I believe this has something to do with the s2 geometry engine behaving in an unexpected fashion.
TL;DR: consider using sf_use_s2(F)
in your code.
Long version:
library(sf)
library(dplyr)
library(mapview)
set.seed(80085)
random_points <- tibble(Lon = runif(1000,-180,180),
Lat = runif(1000,-90,90)) %>%
st_as_sf(coords=1:2, remove=F, crs=4326)
mapview(random_points) # this is "truth"
area_of_interest <- matrix(c(-160, -60,
150, -60,
150, 60,
-160, 60,
-160, -60),
byrow = TRUE,
ncol = 2) %>%
list() %>%
st_polygon() %>%
st_sfc(crs = 4326)
mapview(area_of_interest) # this is our area of interest
# an atribute of points - in AOI or not?
random_points$aoi <- st_contains(area_of_interest,
random_points,
sparse = F) %>%
t() %>%
c()
# a visual overview; this is _not_ expected!
# the topology of AOI was not applied correctly
mapview(random_points, zcol = "aoi")
# let us try turning S2 engine off, and fall back to good old GEOS
sf_use_s2(F)
# exactly the same code as before!!
random_points$aoi <- st_contains(area_of_interest,
random_points,
sparse = F) %>%
t() %>%
c()
# but the output behaves much better!
mapview(random_points, zcol = "aoi")
# a seletion of random points; cropped to area of interest
library(ggplot2)
random_points %>%
filter(aoi) %>%
ggplot() + geom_sf(pch = 4, color = "red")