Choropleth Map of State Population

Question

Trying to create a choropleth map showing state population also labeling capital cities. I had two data frame initially but was not able not add ggplot 1 to ggplot 2, so I combined two data frames together, part of the table looks like this:

basically trying to combines these two images together:

and

I've written

ggplot(spr, aes(long, lat)) + borders("state") + geom_point() + 
coord_quickmap() +geom_label_repel(aes(label = city), size = 2) + 
geom_polygon(aes(long, lat, group = capital, fill = pcls),color = "grey") +
coord_map("bonne", parameters=45) +ggthemes::theme_map() + 
scale_fill_brewer(palette = "Reds")

but map looks off:

i think it's the polygon part is throwing me off but not sure what to do about it.

Answer 1

You'll need shapefiles, or at least have the borders known to map the data to.

In keeping with your question from the other day, you can still use state . scale_fill_brewer is designed for use with discrete variables. Use scale_fill_gradientn , specifying brewer.pal . Add the capitals layer in there as desired.

library(ggplot2)
library(usmap)
library(maps)
library(ggrepel)
library(ggthemes)

us <- map_data("state") # get the data to plot and map data to
data(statepop)
pops <- statepop
pops$full <- tolower(pops$full)

ggplot() + geom_map(data = us, map = us, aes(long, lat, map_id = region), fill = "#ffffff", color = "#ffffff", size = 0.15) +
  geom_map(data = pops, map = us, aes(fill = pop_2015, map_id = full), size = 0.15) +
  coord_map("bonne", parameters=45) +
  scale_fill_gradientn(colors = brewer.pal(9, "Reds")) + #adjust the number as necessary
  borders("state") +
  ggthemes::theme_map()