2

Using R, I am attempting to create a plot that contains both geom_spatraster and geom_spatvector objects, and I am running into issues with the legend. Using the repex at the bottom below, the legend for the pts points show up in every color from the spatraster (first screenshot below). (I'm not needing to include the pol variable in the legend.) Is there a way to plot the pts spatvector variable and have it listed separately in the legend, like the second screenshot below?

current plot output desired plot output

library(terra)
library(tidyterra)
library(ggplot2)

#create raster
df <- data.frame(x=rep(c(0.5,1.5,2.5), by=3),
           y=rep(c(3.5, 2.5, 1.5, 0.5), each=3),
           z = 1:12)

r <- rast(df, type="xyz", crs="epsg:4326")

#raster color table
ctbl <- data.frame(value=1:12,
                   col=colors()[sample.int(length(colors()), 12, replace = FALSE)])
coltab(r) <- ctbl    #apply to raster

cls <- data.frame(id    = 1:12,
                  cat = letters[1:12])
levels(r) <- cls         #apply to raster
plot(r)

#create "state" polygon
pol <- vect(list(rbind(c(0.5,3.5), c(0.5,0.5), c(2.5,0.5), c(2.5,3.5), c(0.5,3.5))),
            "polygons",
            crs="epsg:4326")
pol$name <- "state name"
plot(pol, add=TRUE)
#create "station" points
pts <- vect(list(rbind(c(2,2), c(1.5,3.2), c(0.6,2.8))),
            "points",
            crs="epsg:4326")
pts$stn_names <- sprintf("station %s", 1:3)
plot(pts, add=TRUE)

#plot
ggplot() +
  geom_spatraster(data=r,
                  use_coltab=TRUE,
                  name="Land cover") +
  geom_spatvector(data = pol,
                  fill = NA,
                  linewidth=0.8,
                  color="#282828", 
                  show.legend=FALSE) +
  geom_spatvector(data=pts, 
                  shape=24, size=3, 
                  col="black", 
                  fill="magenta", 
                  show.legend = TRUE)
Improve this question

1 Answer 1

Reset to default
2

To get a separate legend map on the shape aesthetic instead of setting the shape as a parameter and use e.g. scale_shape_identity. Additionally I explicitly set the order of the legends via guide_legend.

library(terra)
library(tidyterra)
library(ggplot2)

set.seed(456)

ggplot() +
  geom_spatraster(
    data = r,
    use_coltab = TRUE
  ) +
  geom_spatvector(
    data = pol,
    fill = NA,
    linewidth = 0.8,
    color = "#282828",
    show.legend = FALSE
  ) +
  geom_spatvector(
    data = pts,
    aes(shape = 24),
    size = 3,
    color = "black",
    fill = "magenta"
  ) +
  scale_shape_identity(
    labels = "Stations",
    guide = guide_legend(order = 2), 
    name = NULL
  ) +
  labs(fill = "Land cover") +
  guides(fill = guide_legend(order = 1)) +
  theme(
    # Remove grey bg
    legend.key = element_rect(fill = NA),
    # Uncomment to remove the space between the legends
    #legend.spacing.y = unit(0, "pt"),
    #legend.margin = margin()
  )

enter image description here

Improve this answer
Sign up to request clarification or add additional context in comments.

Comments

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.