🗺 usmap

Original R package comes from: https://github.com/pdil/usmap, which is created by Paolo Di Lorenzo.

The Pkgdown website link: https://jhu-statprogramming-fall-2023.github.io/biostat777-project3-part1-yyingying00; the website and the Example Analysis were created by Yingying Yu.

5 things customized in the pkgdown website:

• Added a bootswatch theme flatly

• Edited the sidebar to exclude community

• Rearranged the navbar

• Reordered the link on the Articles

• Changed the footer to include my name

View code used to generate these plots: resources/examples.R

Purpose

Typically in R it is difficult to create nice US choropleths that include Alaska and Hawaii. The functions presented here attempt to elegantly solve this problem by manually moving these states to a new location and providing a fortified data frame for mapping and visualization. This allows the user to easily add data to color the map.

Shape Files

The shape files that we use to plot the maps in R are located in the usmapdata package. These are generated from the US Census Bureau cartographic boundary files. Maps at both the state and county levels are included for convenience.

Update History

Date	usmap version	Shape File Year	Link
February 27, 2022	0.6.0	2020	🔗
June 3, 2018	0.3.0	2017	🔗
January 29, 2017	0.1.0	2015	🔗

Installation

To install from CRAN (recommended), run the following code in an R console:

install.packages("usmap")

To install the package from this repository, run the following code in an R console:

# install.package("devtools")
devtools::install_github("pdil/usmap")

Installing using devtools::install_github will provide the most recent developer build of usmap.

⚠️ The developer build may be unstable and not function correctly, use with caution.

To begin using usmap, import the package using the library command:

library(usmap)

Documentation

To read the package vignettes, which explain helpful uses of the package, use vignette:

vignette(package = "usmap")
vignette("introduction", package = "usmap")
vignette("mapping", package = "usmap")
vignette("advanced-mapping", package = "usmap")

For further help with this package, open an issue or ask a question on Stackoverflow with the usmap tag.

Features

• Obtain map with certain region breakdown

state_map <- us_map(regions = "states")

str(state_map)

  #> 'data.frame':  13696 obs. of  9 variables:
  #> $ x    : num  1093752 1093244 1093125 1092939 1092914 ...
  #> $ y    : num  -1378545 -1374233 -1360891 -1341458 -1338952 ...
  #> $ order: int  1 2 3 4 5 6 7 8 9 10 ...
  #> $ hole : logi  FALSE FALSE FALSE FALSE FALSE FALSE ...
  #> $ piece: int  1 1 1 1 1 1 1 1 1 1 ...
  #> $ group: chr  "01.1" "01.1" "01.1" "01.1" ...
  #> $ fips : chr  "01" "01" "01" "01" ...
  #> $ abbr : chr  "AL" "AL" "AL" "AL" ...
  #> $ full : chr  "Alabama" "Alabama" "Alabama" "Alabama" ...

county_map <- us_map(regions = "counties")

str(county_map)

  #> 'data.frame':  55097 obs. of  10 variables:
  #> $ x     : num  811200 829408 828835 855600 859265 ...
  #> $ y     : num  -821207 -819722 -814641 -811770 -846158 ...
  #> $ order : int  1 2 3 4 5 6 7 8 9 10 ...
  #> $ hole  : logi  FALSE FALSE FALSE FALSE FALSE FALSE ...
  #> $ piece : int  1 1 1 1 1 1 1 1 1 1 ...
  #> $ group : chr  "01001.1" "01001.1" "01001.1" "01001.1" ...
  #> $ fips  : chr  "01001" "01001" "01001" "01001" ...
  #> $ abbr  : chr  "AL" "AL" "AL" "AL" ...
  #> $ full  : chr  "Alabama" "Alabama" "Alabama" "Alabama" ...
  #> $ county: chr  "Autauga County" "Autauga County" "Autauga County" "Autauga County" ...

• Look up FIPS codes for states and counties

fips("New Jersey")
#> "34"

fips(c("AZ", "CA", "New Hampshire"))
#> "04" "06" "33"

fips("NJ", county = "Mercer")
#> "34021"

fips("NJ", county = c("Bergen", "Hudson", "Mercer"))
#> "34003" "34017" "34021"

• Retrieve states or counties with FIPS codes

fips_info(c("34", "35"))
#>         full abbr fips
#> 1 New Jersey   NJ   34 
#> 2 New Mexico   NM   35

fips_info(c("34021", "35021"))
#>         full abbr         county  fips
#> 1 New Jersey   NJ  Mercer County 34021
#> 2 New Mexico   NM Harding County 35021

• Add FIPS codes to data frame

data <- data.frame(
  state = c("NJ", "NJ", "NJ", "PA"),
  county = c("Bergen", "Hudson", "Mercer", "Allegheny")
)

library(dplyr)
data %>% rowwise %>% mutate(fips = fips(state, county))

#>   state     county  fips
#> 1    NJ     Bergen 34003
#> 2    NJ     Hudson 34017
#> 3    NJ     Mercer 34021
#> 4    PA  Allegheny 42003

• Plot US maps

plot_usmap("states")
plot_usmap("counties")

• Display only certain states, counties, or regions

plot_usmap("states", include = .mountain, labels = TRUE)

plot_usmap("counties", data = countypov, values = "pct_pov_2014", include = "FL") +
    ggplot2::scale_fill_continuous(low = "green", high = "red", guide = FALSE)

plot_usmap("counties", data = countypop, values = "pop_2015", include = .new_england) + 
    ggplot2::scale_fill_continuous(low = "blue", high = "yellow", guide = FALSE)

Additional Information

Projection

usmap uses an Albers equal-area conic projection, with arguments as follows:

usmap::usmap_crs()

  #> Coordinate Reference System:
  #> Deprecated Proj.4 representation:
  #>  +proj=laea +lat_0=45 +lon_0=-100 +x_0=0 +y_0=0 +ellps=sphere
  #> +units=m +no_defs 
  #> WKT2 2019 representation:
  #> PROJCRS["unknown",
  #>     BASEGEOGCRS["unknown",
  #>         DATUM["unknown",
  #>             ELLIPSOID["Normal Sphere (r=6370997)",6370997,0,
  #>                 LENGTHUNIT["metre",1,
  #>                     ID["EPSG",9001]]]],
  #>         PRIMEM["Greenwich",0,
  #>             ANGLEUNIT["degree",0.0174532925199433],
  #>             ID["EPSG",8901]]],
  #>     CONVERSION["unknown",
  #>         METHOD["Lambert Azimuthal Equal Area (Spherical)",
  #>             ID["EPSG",1027]],
  #>         PARAMETER["Latitude of natural origin",45,
  #>             ANGLEUNIT["degree",0.0174532925199433],
  #>             ID["EPSG",8801]],
  #>         PARAMETER["Longitude of natural origin",-100,
  #>             ANGLEUNIT["degree",0.0174532925199433],
  #>             ID["EPSG",8802]],
  #>         PARAMETER["False easting",0,
  #>             LENGTHUNIT["metre",1],
  #>             ID["EPSG",8806]],
  #>         PARAMETER["False northing",0,
  #>             LENGTHUNIT["metre",1],
  #>             ID["EPSG",8807]]],
  #>     CS[Cartesian,2],
  #>         AXIS["(E)",east,
  #>             ORDER[1],
  #>             LENGTHUNIT["metre",1,
  #>                 ID["EPSG",9001]]],
  #>         AXIS["(N)",north,
  #>             ORDER[2],
  #>             LENGTHUNIT["metre",1,
  #>                 ID["EPSG",9001]]]] 

This is the same projection used by the US National Atlas.

To obtain the projection used by usmap, use usmap_crs().

Alternatively, the CRS (coordinate reference system) can be created manually with the following command:

sp::CRS(paste("+proj=laea +lat_0=45 +lon_0=-100 +x_0=0 +y_0=0",
              "+a=6370997 +b=6370997 +units=m +no_defs"))

Acknowledgments

The code used to generate the map files was based on this blog post by Bob Rudis:
Moving The Earth (well, Alaska & Hawaii) With R