Is there any way to add a color palette into the size aesthetic?

Question

I am working in the next code: ggplot()+ geom_sf(data = DPEst_DH, aes(size = di1a), col="orangered") that works.

But I want a colored legend.

In other words, I want apply the same field at two aesthetics, size and color but keeping one legend.

...+ geom_sf(data = DPEst_DH, aes(color=di1a, size=di1a))

With that code line I have the next output but I want to know if is possible to have something like the last image.

Answer 1

One option to achieve your desired result would be to make your di1a column a discrete variable using e.g. cut and to set the colors and sizes via scale_xxx_manual.

Making use of the nc shape file shipped with the sf package as example data:

library(ggplot2)
library(dplyr)

# Example data
nc_center <- sf::st_read(system.file("shape/nc.shp", package = "sf"), quiet = TRUE) %>% 
  sf::st_centroid() 

# Bin numeric variable
labels <- pretty(range(nc_center$AREA))
breaks <- c(labels, Inf)
nc_center <- nc_center %>% 
  mutate(area = cut(AREA, breaks = breaks, labels = labels, right = FALSE))

# Color and size palette
colors <- c("#132B43", "#56B1F7") # Default ggplot2 blue colors used for color gradient
pal <- colorRampPalette(colors)(length(labels))
pal_size <- seq(1, 6, length.out = 5) # c(1, 6): Default range for size scale

ggplot() +
  geom_sf(data = nc_center, aes(color = area, size = area)) +
  scale_color_manual(values = pal) +
  scale_size_manual(values = pal_size)