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Make a Choropleth Map of Continuous Variables with ggplot2 (02_07)

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This lesson is called Make a Choropleth Map of Continuous Variables with ggplot2 (02_07), part of the Mapping with R course. This lesson is called Make a Choropleth Map of Continuous Variables with ggplot2 (02_07), part of the Mapping with R course.

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Transcript

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Your Turn

Solution



          library(tigris)
        
          library(sf)
        
          library(rmapshaper)
        
          library(tidyverse)
        
          library(readxl)
        
          library(janitor)
        
          library(mapview)
        
          library(tidycensus)
        
          

        
          us_states <- states() %>% 
        
            clean_names() %>% 
        
            mutate(statefp = as.numeric(statefp))
        
          

        
          south_atlantic_states <- us_states %>% 
        
            filter(division == 5) %>% 
        
            ms_simplify()
        
          

        
          prisoners_per_state <- get_decennial(geography = "state",
        
                        variables = c("state_prison_population" = "PCT020006")) %>% 
        
            clean_names() %>% 
        
            mutate(state_prison_population = if_else(name == "District of Columbia",
        
                                   NA_real_,
        
                                   value))
        
          

        
          south_atlantic_prisons <- south_atlantic_states %>% 
        
            left_join(prisoners_per_state)
        
          

        
          

        
          # ==== Your turn =====
        
          

        
          south_atlantic_prisons %>% 
        
            ggplot() +
        
            geom_sf(aes(fill = state_prison_population,
        
                        shape = "District of Columbia"),
        
                    size = 0.1,
        
                    color = "white") +
        
            scale_fill_viridis_c(na.value = "pink") +
        
            guides(shape = guide_legend(override.aes = list(fill = "pink",
        
                                                            color = "transparent"),
        
                                        title = NULL,
        
                                        order = 2),
        
                   fill = guide_colorbar(order = 1)) +
        
            theme_void()

For this exercise I took to Twitter to find a dataset that makes DC distinct from the states of US (in 2020).

Use the your-turn script in 02_07w to make this map, ensuring to add a guide item for District of Columbia which does not contain any federal prisons. You’ll need to go through the same steps I did:

Create an NA aeshetic
Override the guide aesthetics
Set the na.value for the fill aesthetic

Learn More

In this video I talk about viridis being the single best choice for a continuous color palette. This is because the color palette works well for folks with colorblindness and is perceptually uniform - which means it's easy to know if you're looking at a low or high value on the scale.

Have any questions? Put them below and we will help you out!

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Mapping with R

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