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3. Advanced Mapping

Paolo Di Lorenzo

2023-12-07

Source: vignettes/advanced-mapping.Rmd
advanced-mapping.Rmd

This vignette will explore some of the more advanced mapping features of usmap. Before continuing, be sure to check out Mapping the US as that will cover more of the basics of plotting US maps and styling them with ggplot2.

Labels

As of usmap 0.4.0, maps with state labels can be created:

usmap::plot_usmap("states", labels = TRUE)

usmap 0.5.0 adds the ability to add county labels:

usmap::plot_usmap("counties", include = c("MA", "CT", "RI"), labels = TRUE)

Labels can be colored using the label_color parameter:

usmap::plot_usmap("counties",
                  include = c("MA", "CT", "RI"),
                  labels = TRUE, label_color = "blue")

ggplot2 aesthetic mapping parameters

Parameters used by the map’s aesthetic mapping (ggplot2::aes) can be passed directly via plot_usmap by adding the parameters anywhere at the call site:

usmap::plot_usmap("counties",
                  include = c("MA", "CT", "RI"),
                  labels = TRUE, label_color = "blue",
                  fill = "yellow", alpha = 0.25, color = "orange", linewidth = 2)

Notice in this case we set the fill and alpha parameters to fill in the counties with a semi-transparent yellow color.

The following parameters are supported:

  • fill: fill color of the state/county polygons
  • alpha: transparency of the state/county polygon fill colors
  • color/colour: line color of the state/county polygons
  • linewidth: thickness of the state/county polygon lines