My question combines two separate issues posted on before on Stackoverflow: i. Adding multiple legends to ggplot and ii. Add line legend to geom_sf.
I would like to add multiple legends to ggplot2
(as in the first post), but am using sf
. This complicates filling up the aesthetic space. The answer suggested in i. above does not work well with multiple types of geometries -- we cannot assign points and lines to a single class and then use factors. In my case, I have several line and point shapefiles, and simply want to add a separate legend entry for each shapefile added.
There seems to be no need to invoke aes()
, but aes()
may be the only way to call a legend.
Reproducible example
I would like to do something similar to the following (borrowing from (i)), but without the as.factor
so that I could have separate calls of geom_sf
:
library(sf)
library(ggplot2)
# reproducible data
lon<-c(5.121420, 6.566502, 4.895168, 7.626135)
lat<-c(52.09074, 53.21938, 52.37022, 51.96066)
cities<-c('utrecht','groningen','amsterdam','munster')
size<-c(300,500,1000,50)
xy.cities<-data.frame(lon,lat,cities,size)
# line example
line1 <- st_linestring(as.matrix(xy.cities[1:2,1:2]))
line2 <- st_linestring(as.matrix(xy.cities[3:4,1:2]))
lines.sfc <- st_sfc(list(line1,line2))
simple.lines.sf <- st_sf(id=1:2,size=c(10,50),geometry=lines.sfc)
ggplot() +
geom_sf(data= simple.lines.sf, aes(colour = as.factor(id)), show.legend = "line")
That is, something more like:
ggplot() +
geom_sf(data= dataset1, color="red" ) +
geom_sf(data= dataset2, color="blue" )