ggplot how to plot pie charts on USA map with state's id

Question

I would like to plot pie charts of different fuel type for each state on USA map. my data includes fuel types and their amount and each state id. I want to know how to plot pie on map for each state with state id?

Thanks,

data <- data.frame(region= c(AL, AR, AZ, CA, IA), 
                  gas= c(25, 45, 45, 60, 75),
                  coal= c(45, 50, 45, 20, 15), 
                  wind= c(30, 5, 10, 20, 10), 
                  solar= c(10, 10, 10, 10, 10))

Answer 1

Update The usmap has been modernized in version 0.7.0 and now returns data as simple features. Hence, getting the coordinates for the scatter pies requires slightly more effort to retrieve the coordinates from the sf object:

library(usmap)
library(ggplot2)
library(scatterpie)

states <- us_map("states")

centroids <- usmapdata::centroid_labels("states")

centroids <- cbind(
  abbr = centroids$abbr,
  sf::st_coordinates(centroids)
) |>
  as.data.frame() |>
  transform(
    X = as.numeric(X),
    Y = as.numeric(Y)
  )

data_merged <- merge(
  data, centroids,
  by.x = "region", by.y = "abbr",
  all.x = TRUE
)

plot_usmap(regions = "states") +
  geom_scatterpie(
    aes(x = X, y = Y),
    data = data_merged, cols = c("gas", "coal", "wind", "solar")
  ) +
  geom_text(aes(X, Y, label = region),
    data = data_merged, vjust = 1, nudge_y = -100000
  )

Original answer

Using the usmap and the scatterpie packages this could be achieved via ggplot2 like so:

1. Add coordinates for the pies to your data. In the code below I use the coordinates of the state centers provided by usmapdata::centroid_labels
2. Add the pies from your data via geom_scatterpie

library(usmap)
library(ggplot2)
library(scatterpie)

states <- us_map("states")

centroids <- usmapdata::centroid_labels("states")[c("x", "y", "abbr")]

data <- merge(data, centroids, by.x = "region", by.y = "abbr", all.x = TRUE)

plot_usmap(regions = "states") +
  geom_scatterpie(aes(x, y, group = region),
    data = data, cols = c("gas", "coal", "wind", "solar")
  ) +
  geom_text(aes(x, y, label = region),
            data = data, vjust = 1, nudge_y = -100000
  )

EDIT If you want to exclude some states (or include only some states) you could do so via the exclude or include argument of plot_usmap:

plot_usmap(regions = "states", exclude = c("AK", "HI")) +
  geom_scatterpie(aes(x, y, group = region),
                  data = data, cols = c("gas", "coal", "wind", "solar")
  ) +
  geom_text(aes(x, y, label = region),
            data = data, vjust = 1, nudge_y = -100000
  )

DATA

data <- data.frame(
  region = c("AL", "AR", "AZ", "CA", "IA"),
  gas = c(25, 45, 45, 60, 75),
  coal = c(45, 50, 45, 20, 15),
  wind = c(30, 5, 10, 20, 10),
  solar = c(10, 10, 10, 10, 10)
)