尝试按结果变量为县着色时 R plot_usmap() 中的错误

Question

I'm trying to map an outcome measured at the county-level in Idaho. I'm not understanding the error message below. The following code reproduces the error. I've tried limiting map.data to just one row per county, but this also results in an error.

require(usmap)
require(ggplot2)

map.data <- usmap::us_map("counties",
                          include = "ID")
dim(map.data)
1090   10

random outcome values for plotting by county

n.county <- length(unique(map.data$fips))
set.seed(0)
d <- data.frame( fips = unique(map.data$fips),
                 values = runif(n.county))
head(d)
    fips    values
 1 16001 0.8966972
 2 16003 0.2655087
 3 16005 0.3721239
 4 16007 0.5728534
 5 16009 0.9082078
 6 16011 0.2016819

merge to add "values" variable to map.data

map.data <- merge( map.data, d)
map.data <- map.data[ , c("fips", "values")]
dim(map.data)
1090   2

plot_usmap( regions = "counties",
            include = "ID", 
            data = map.data,
            values = "values") + 
  labs( title = "Idaho",
        subtitle = "Outcome Y") 

R error:

This is the R error I get:

Don't know how to automatically pick scale for object of type data.frame. Defaulting to continuous.
Error: Aesthetics must be either length 1 or the same as the data (35884): fill

Next, I planned to color the counties based on the "values" using the following:

  + scale_fill_continuous( low = "white", 
                           high = "red", 
                           name = "Legend", 
                           label = scales::comma) + 
  theme( legend.position = "right")

Answer 1

Apparently, the problem comes from the name of the second column of your dataframe, that you called "values". Maybe plot_usmap breaks when the argument values calls a column called values .

Your code works when the name of that column is "X" for example:

require(usmap)
require(ggplot2)

map.data <- usmap::us_map("counties", include = "ID")
dim(map.data)
n.county <- length(unique(map.data$fips))
set.seed(0)
d <- data.frame( fips = unique(map.data$fips),
                 X = runif(n.county))
head(d)

map.data <- merge( map.data, d)
map.data <- map.data[ , c("fips", "X")]
dim(map.data)
1090   2

plot_usmap( regions = "counties",
            include = "ID", 
            data = map.data,
            values = "X") + 
  labs( title = "Idaho",
        subtitle = "Outcome Y")