Merge branch 'master' into master

DESCRIPTION

@@ -1,10 +1,10 @@
 Package: albersusa
 Type: Package
 Title: Tools, Shapefiles & Data to Work with an 'AlbersUSA' Composite Projection
-Version: 0.2.0
-Date: 2016-03-29
-Author: Bob Rudis (@hrbrmstr)
-Maintainer: Bob Rudis <bob@rudis.net>
+Version: 0.3.0
+Date: 2017-01-26
+Author: Bob Rudis (bob@rud.is)
+Maintainer: Bob Rudis <bob@rud.is>
 Description: Creating a composite projection for states and counties of the United States
     that includes scaled and shifted polygons for Alaska and Hawaii is time consuming
     and potentially error-prone. Functions and data sets are provided to make it easier to
@@ -15,11 +15,13 @@ BugReports: https://github.com/hrbrmstr/albersusa/issues
 License: AGPL
 Suggests:
     testthat,
-    ggalt
+    ggalt,
+    tibble
 Depends:
     R (>= 3.0.0)
 Imports:
     sp,
+    sf,
     rgeos,
     rgdal,
     maptools

NAMESPACE

@@ -2,13 +2,16 @@
 
 export(counties_composite)
 export(points_elided)
+export(counties_sf)
 export(us_aeqd_proj)
 export(us_eqdc_proj)
 export(us_laea_proj)
 export(us_lcc_proj)
 export(us_longlat_proj)
 export(usa_composite)
+export(usa_sf)
 import(maptools)
 import(rgdal)
 import(rgeos)
+import(sf)
 import(sp)

NEWS.md

@@ -1,2 +1,5 @@
+0.3.0
+* simplefeatures (sf) functions
+
 0.1.0 
 * Initial release

R/albersusa-package.R

@@ -6,6 +6,9 @@
 #' produce maps with a composite projection. Furthermore, named projections for common
 #' transormations are provided to further increase mapping productivity.
 #'
+#' Newer \code{sf} (simple features) objects can be returned or legacy R
+#' spatial \code{sp} objects can be returned.
+#'
 #' Reference GeoJSON files are provided in the following locations (i.e. you can use
 #' them in any mapping program):
 #'
@@ -16,6 +19,7 @@
 #'
 #' @name albersusa
 #' @docType package
-#' @author Bob Rudis (@@hrbrmstr)
+#' @author Bob Rudis (bob@@rud.is)
 #' @import sp rgeos rgdal maptools
+#' @import sf
 NULL

R/counties.r

@@ -60,4 +60,4 @@ counties_composite <- function(proj=c("longlat", "laea", "lcc", "eqdc", "aeqd"))
 
   cty
 
-}
+}

R/counties_sf.r

@@ -0,0 +1,62 @@
+#' Retreive a U.S. county composite map, optionally with a projection, as a simplefeature
+#'
+#' The \code{proj} parameter is intende to simplify usage for those using base
+#' plotting. If anything but \code{longlat} is specified the composite map
+#' will be pre-projected to those
+#'
+#' This is what's in the object looks like:
+#'
+#' \preformatted{
+#' Observations: 3,143
+#' Variables: 9
+#' $ fips        <fctr> 01001, 01009, 01017, 01021, 01033, 01045, 01051, 01065, 01079, 0...
+#' $ state_fips  <fctr> 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 05, 05, 06, ...
+#' $ county_fips <fctr> 001, 009, 017, 021, 033, 045, 051, 065, 079, 083, 099, 107, 121,...
+#' $ name        <fctr> Autauga, Blount, Chambers, Chilton, Colbert, Dale, Elmore, Hale,...
+#' $ lsad        <fctr> County, County, County, County, County, County, County, County, ...
+#' $ census_area <dbl> 594.436, 644.776, 596.531, 692.854, 592.619, 561.150, 618.485, 64...
+#' $ state       <fctr> Alabama, Alabama, Alabama, Alabama, Alabama, Alabama, Alabama, A...
+#' $ iso_3166_2  <fctr> AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AR, AR, CA, ...
+#' $ geometry    <simple_feature> MULTIPOLYGON(((-86.496774 3..., MULTIPOLYGON(((-86.577...#' }
+#'
+#' A reference GeoJSON file isprovided in the following location (i.e. you can use
+#' it in any mapping program):
+#'
+#' \preformatted{
+#' system.file("extdata/composite_us_counties.geojson.gz", package="albersusa")
+#' }
+#'
+#' @param proj if anything but \code{longlat} is specified, the shapefile will
+#'        be pre-projected before being returned
+#' @export
+#' @examples
+#' library(sf)
+#'
+#' plot(counties_sf()) # these take a while to render
+#' plot(counties_sf("laea"))
+counties_sf <- function(proj=c("longlat", "laea", "lcc", "eqdc", "aeqd")) {
+
+  # us <- readOGR(system.file("extdata/composite_us_counties.geojson", package="albersusa"),
+  #               "OGRGeoJSON",
+  #               stringsAsFactors=FALSE,
+  #               verbose=FALSE)
+
+  cty <- readRDS(system.file("extdata/counties_sf.rda", package="albersusa"))
+
+  proj <- match.arg(proj, c("longlat", "laea", "lcc", "eqdc", "aeqd"))
+
+  if (proj != "longlat") {
+
+    proj <- switch(proj,
+                   laea=us_laea_proj,
+                   lcc=us_lcc_proj,
+                   eqdc=us_eqdc_proj,
+                   aeqd=us_aeqd_proj)
+
+    cty <- sf::st_transform(cty, proj)
+
+  }
+
+  cty
+
+}

R/states_sf.r

@@ -0,0 +1,67 @@
+#' Retreive a U.S. state composite map, optionally with a projection, as a simplefeature
+#'
+#' The \code{proj} parameter is intende to simplify usage for those using base
+#' plotting. If anything but \code{longlat} is specified the composite map
+#' will be pre-projected to those
+#'
+#' This is what's the object looks like:
+#'
+#' \preformatted{
+#' Observations: 51
+#' Variables: 14
+#' $ geo_id              <fctr> 0400000US04, 0400000US05, 0400000US06, 0400000US08, 0400...
+#' $ fips_state          <fctr> 04, 05, 06, 08, 09, 11, 13, 17, 18, 22, 27, 28, 30, 35, ...
+#' $ name                <fctr> Arizona, Arkansas, California, Colorado, Connecticut, Di...
+#' $ lsad                <fctr> , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
+#' $ census_area         <dbl> 113594.084, 52035.477, 155779.220, 103641.888, 4842.355, ...
+#' $ iso_3166_2          <fctr> AZ, AR, CA, CO, CT, DC, GA, IL, IN, LA, MN, MS, MT, NM, ...
+#' $ census              <int> 6392017, 2915918, 37253956, 5029196, 3574097, 601723, 968...
+#' $ pop_estimataes_base <int> 6392310, 2915958, 37254503, 5029324, 3574096, 601767, 968...
+#' $ pop_2010            <int> 6411999, 2922297, 37336011, 5048575, 3579345, 605210, 971...
+#' $ pop_2011            <int> 6472867, 2938430, 37701901, 5119661, 3590537, 620427, 981...
+#' $ pop_2012            <int> 6556236, 2949300, 38062780, 5191709, 3594362, 635040, 991...
+#' $ pop_2013            <int> 6634997, 2958765, 38431393, 5272086, 3599341, 649111, 999...
+#' $ pop_2014            <int> 6731484, 2966369, 38802500, 5355866, 3596677, 658893, 100...
+#' $ geometry            <list> [-112.53859, -112.53454, -112.36895, -112.35769, -111.41...#' }
+#'
+#' A reference GeoJSON file is provided in the following location (i.e. you can use
+#' it in any mapping program):
+#'
+#' \preformatted{
+#' system.file("extdata/composite_us_states.geojson.gz", package="albersusa")
+#' }
+#'
+#' @param proj if anything but \code{longlat} is specified, the shapefile will
+#'        be pre-projected before being returned
+#' @export
+#' @examples
+#' library(sf)
+#'
+#' plot(usa_sf()) # these take a while to render
+#' plot(usa_sf("laea"))
+usa_sf <- function(proj=c("longlat", "laea", "lcc", "eqdc", "aeqd")) {
+
+  # us <- readOGR(system.file("extdata/composite_us_states.geojson", package="albersusa"),
+  #               "OGRGeoJSON",
+  #               stringsAsFactors=FALSE,
+  #               verbose=FALSE)
+
+  us <- readRDS(system.file("extdata/states_sf.rda", package="albersusa"))
+
+  proj <- match.arg(proj, c("longlat", "laea", "lcc", "eqdc", "aeqd"))
+
+  if (proj != "longlat") {
+
+    proj <- switch(proj,
+                   laea=us_laea_proj,
+                   lcc=us_lcc_proj,
+                   eqdc=us_eqdc_proj,
+                   aeqd=us_aeqd_proj)
+
+    us <- sf::st_transform(us, proj)
+
+  }
+
+  us
+
+}

README.Rmd

@@ -7,21 +7,28 @@ output: rmarkdown::github_document
 
 The following functions are implemented:
 
+- `counties_sf`:	Retreive a U.S. county composite map, optionally with a projection, as a simplefeature
+- `usa_sf`:	Retreive a U.S. state composite map, optionally with a projection, as a simplefeature
+
+Some legacy ones:
+
 - `usa_composite`:	Retreive a U.S. composite map, optionally with a projection
+- `counties_composite`:	Retreive a U.S. county composite map, optionally with a projection
+
+Pre-canned projection strings:
+
 - `us_aeqd_proj`:	Oblique azimuthal equidistant convenience projection
 - `us_eqdc_proj`:	Equidistant conic convenience projection
 - `us_laea_proj`:	Albers equal-area conic convenience projection
 - `us_lcc_proj`:	Lambert conformal conic convenience projection
 - `us_longlat_proj`:	Generic long/lat convenience projection
-- `counties_composite`:	Retreive a U.S. county composite map, optionally with a projection
 
 The following data sets are included:
 
 - `system.file("extdata/composite_us_states.geojson.gz", package="albersusa")` 
 - `system.file("extdata/composite_us_counties.geojson.gz", package="albersusa")`
 
-Also, the `@data` slot of each `SpatialPolygonsDataFrame` has some handy data you can 
-use (like FIPS codes and state/county population information).
+Also, the simplefeatures coluns and `@data` slot of each `SpatialPolygonsDataFrame` has some handy data you can use (like FIPS codes and state/county population information).
 
 ### Installation
 
@@ -37,6 +44,7 @@ options(width=120)
 
 ```{r message=FALSE, fig.retina=2}
 library(albersusa)
+library(sf)
 library(sp)
 library(rgeos)
 library(maptools)
@@ -48,7 +56,23 @@ library(scales)
 
 # current verison
 packageVersion("albersusa")
+```
+
+### Simple features
 
+```{r message=FALSE, fig.retina=2}
+par(mar=c(0,0,1,0))
+
+us_sf <- usa_sf("laea")
+plot(us_sf["pop_2012"])
+
+cty_sf <- counties_sf("aeqd")
+plot(cty_sf["census_area"])
+```
+
+### Legacy
+
+```{r message=FALSE, warning=FALSE, fig.retina=2}
 us <- usa_composite()
 
 dplyr::glimpse(us@data)
@@ -134,4 +158,3 @@ date()
 
 test_dir("tests/")
 ```
-

README.md

@@ -5,20 +5,28 @@
 
 The following functions are implemented:
 
+-   `counties_sf`: Retreive a U.S. county composite map, optionally with a projection, as a simplefeature
+-   `usa_sf`: Retreive a U.S. state composite map, optionally with a projection, as a simplefeature
+
+Some legacy ones:
+
 -   `usa_composite`: Retreive a U.S. composite map, optionally with a projection
+-   `counties_composite`: Retreive a U.S. county composite map, optionally with a projection
+
+Pre-canned projection strings:
+
 -   `us_aeqd_proj`: Oblique azimuthal equidistant convenience projection
 -   `us_eqdc_proj`: Equidistant conic convenience projection
 -   `us_laea_proj`: Albers equal-area conic convenience projection
 -   `us_lcc_proj`: Lambert conformal conic convenience projection
 -   `us_longlat_proj`: Generic long/lat convenience projection
--   `counties_composite`: Retreive a U.S. county composite map, optionally with a projection
 
 The following data sets are included:
 
 -   `system.file("extdata/composite_us_states.geojson.gz", package="albersusa")`
 -   `system.file("extdata/composite_us_counties.geojson.gz", package="albersusa")`
 
-Also, the `@data` slot of each `SpatialPolygonsDataFrame` has some handy data you can use (like FIPS codes and state/county population information).
+Also, the simplefeatures coluns and `@data` slot of each `SpatialPolygonsDataFrame` has some handy data you can use (like FIPS codes and state/county population information).
 
 ### Installation
 
@@ -30,6 +38,7 @@ devtools::install_github("hrbrmstr/albersusa")
 
 ``` r
 library(albersusa)
+library(sf)
 library(sp)
 library(rgeos)
 library(maptools)
@@ -43,7 +52,27 @@ library(scales)
 packageVersion("albersusa")
 ```
 
-    ## [1] '0.2.0'
+    ## [1] '0.3.0'
+
+### Simple features
+
+``` r
+par(mar=c(0,0,1,0))
+
+us_sf <- usa_sf("laea")
+plot(us_sf["pop_2012"])
+```
+
+<img src="README_files/figure-markdown_github/unnamed-chunk-4-1.png" width="672" />
+
+``` r
+cty_sf <- counties_sf("aeqd")
+plot(cty_sf["census_area"])
+```
+
+<img src="README_files/figure-markdown_github/unnamed-chunk-4-2.png" width="672" />
+
+### Legacy
 
 ``` r
 us <- usa_composite()
@@ -71,14 +100,14 @@ dplyr::glimpse(us@data)
 plot(us, lwd=0.25)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-1.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-1.png" width="672" />
 
 ``` r
 us <- usa_composite("laea")
 plot(us, lwd=0.25)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-2.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-2.png" width="672" />
 
 ``` r
 us <- usa_composite()
@@ -88,57 +117,48 @@ gg <- ggplot()
 gg <- gg + geom_map(data=us_map, map=us_map,
                     aes(x=long, y=lat, map_id=id),
                     color="#2b2b2b", size=0.1, fill=NA)
-```
-
-    ## Warning: Ignoring unknown aesthetics: x, y
-
-``` r
 gg <- gg + theme_map()
-```
 
-    ## Warning: `panel.margin` is deprecated. Please use `panel.spacing` property instead
-
-``` r
 gg + coord_map()
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-3.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-3.png" width="672" />
 
 ``` r
 gg + coord_map("polyconic")
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-4.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-4.png" width="672" />
 
 ``` r
 gg + coord_proj()
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-5.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-5.png" width="672" />
 
 ``` r
 gg + coord_proj(us_laea_proj)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-6.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-6.png" width="672" />
 
 ``` r
 gg + coord_proj(us_aeqd_proj)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-7.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-7.png" width="672" />
 
 ``` r
 gg + coord_proj(us_eqdc_proj)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-8.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-8.png" width="672" />
 
 ``` r
 gg + coord_proj(us_lcc_proj)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-9.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-9.png" width="672" />
 
 ``` r
 gg + 
@@ -151,7 +171,7 @@ gg +
         legend.key.width=unit(3, "lines"))
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-10.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-10.png" width="672" />
 
 ``` r
 us <- counties_composite()
@@ -174,14 +194,14 @@ dplyr::glimpse(us@data)
 plot(us, lwd=0.25)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-11.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-11.png" width="672" />
 
 ``` r
 us <- counties_composite("laea")
 plot(us, lwd=0.25)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-12.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-12.png" width="672" />
 
 ``` r
 us <- counties_composite()
@@ -191,57 +211,48 @@ gg <- ggplot()
 gg <- gg + geom_map(data=us_map, map=us_map,
                     aes(x=long, y=lat, map_id=id),
                     color="#2b2b2b", size=0.1, fill=NA)
-```
-
-    ## Warning: Ignoring unknown aesthetics: x, y
-
-``` r
 gg <- gg + theme_map()
-```
-
-    ## Warning: `panel.margin` is deprecated. Please use `panel.spacing` property instead
 
-``` r
 gg + coord_map()
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-13.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-13.png" width="672" />
 
 ``` r
 gg + coord_map("polyconic")
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-14.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-14.png" width="672" />
 
 ``` r
 gg + coord_proj()
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-15.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-15.png" width="672" />
 
 ``` r
 gg + coord_proj(us_laea_proj)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-16.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-16.png" width="672" />
 
 ``` r
 gg + coord_proj(us_aeqd_proj)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-17.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-17.png" width="672" />
 
 ``` r
 gg + coord_proj(us_eqdc_proj)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-18.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-18.png" width="672" />
 
 ``` r
 gg + coord_proj(us_lcc_proj)
 ```
 
-<img src="README_files/figure-markdown_github/unnamed-chunk-3-19.png" width="672" />
+<img src="README_files/figure-markdown_github/unnamed-chunk-5-19.png" width="672" />
 
 ### Test Results
 
@@ -252,7 +263,7 @@ library(testthat)
 date()
 ```
 
-    ## [1] "Mon Dec 19 16:02:00 2016"
+    ## [1] "Thu Jan 26 23:49:15 2017"
 
 ``` r
 test_dir("tests/")
@@ -262,4 +273,3 @@ test_dir("tests/")
     ## OK: 6 SKIPPED: 0 FAILED: 0
     ## 
     ## DONE ===================================================================================================================
-    ## You rock!

man/albersusa.Rd

@@ -13,6 +13,9 @@ produce maps with a composite projection. Furthermore, named projections for com
 transormations are provided to further increase mapping productivity.
 }
 \details{
+Newer \code{sf} (simple features) objects can be returned or legacy R
+spatial \code{sp} objects can be returned.
+
 Reference GeoJSON files are provided in the following locations (i.e. you can use
 them in any mapping program):
 
@@ -22,6 +25,6 @@ system.file("extdata/composite_us_counties.geojson.gz", package="albersusa")
 }
 }
 \author{
-Bob Rudis (@hrbrmstr)
+Bob Rudis (bob@rud.is)
 }
 

man/counties_sf.Rd

@@ -0,0 +1,47 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/counties_sf.r
+\name{counties_sf}
+\alias{counties_sf}
+\title{Retreive a U.S. county composite map, optionally with a projection, as a simplefeature}
+\usage{
+counties_sf(proj = c("longlat", "laea", "lcc", "eqdc", "aeqd"))
+}
+\arguments{
+\item{proj}{if anything but \code{longlat} is specified, the shapefile will
+be pre-projected before being returned}
+}
+\description{
+The \code{proj} parameter is intende to simplify usage for those using base
+plotting. If anything but \code{longlat} is specified the composite map
+will be pre-projected to those
+}
+\details{
+This is what's in the object looks like:
+
+\preformatted{
+Observations: 3,143
+Variables: 9
+$ fips        <fctr> 01001, 01009, 01017, 01021, 01033, 01045, 01051, 01065, 01079, 0...
+$ state_fips  <fctr> 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 01, 05, 05, 06, ...
+$ county_fips <fctr> 001, 009, 017, 021, 033, 045, 051, 065, 079, 083, 099, 107, 121,...
+$ name        <fctr> Autauga, Blount, Chambers, Chilton, Colbert, Dale, Elmore, Hale,...
+$ lsad        <fctr> County, County, County, County, County, County, County, County, ...
+$ census_area <dbl> 594.436, 644.776, 596.531, 692.854, 592.619, 561.150, 618.485, 64...
+$ state       <fctr> Alabama, Alabama, Alabama, Alabama, Alabama, Alabama, Alabama, A...
+$ iso_3166_2  <fctr> AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AR, AR, CA, ...
+$ geometry    <simple_feature> MULTIPOLYGON(((-86.496774 3..., MULTIPOLYGON(((-86.577...#' }
+
+A reference GeoJSON file isprovided in the following location (i.e. you can use
+it in any mapping program):
+
+\preformatted{
+system.file("extdata/composite_us_counties.geojson.gz", package="albersusa")
+}
+}
+\examples{
+library(sf)
+
+plot(counties_sf()) # these take a while to render
+plot(counties_sf("laea"))
+}
+

man/usa_sf.Rd

@@ -0,0 +1,52 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/states_sf.r
+\name{usa_sf}
+\alias{usa_sf}
+\title{Retreive a U.S. state composite map, optionally with a projection, as a simplefeature}
+\usage{
+usa_sf(proj = c("longlat", "laea", "lcc", "eqdc", "aeqd"))
+}
+\arguments{
+\item{proj}{if anything but \code{longlat} is specified, the shapefile will
+be pre-projected before being returned}
+}
+\description{
+The \code{proj} parameter is intende to simplify usage for those using base
+plotting. If anything but \code{longlat} is specified the composite map
+will be pre-projected to those
+}
+\details{
+This is what's the object looks like:
+
+\preformatted{
+Observations: 51
+Variables: 14
+$ geo_id              <fctr> 0400000US04, 0400000US05, 0400000US06, 0400000US08, 0400...
+$ fips_state          <fctr> 04, 05, 06, 08, 09, 11, 13, 17, 18, 22, 27, 28, 30, 35, ...
+$ name                <fctr> Arizona, Arkansas, California, Colorado, Connecticut, Di...
+$ lsad                <fctr> , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
+$ census_area         <dbl> 113594.084, 52035.477, 155779.220, 103641.888, 4842.355, ...
+$ iso_3166_2          <fctr> AZ, AR, CA, CO, CT, DC, GA, IL, IN, LA, MN, MS, MT, NM, ...
+$ census              <int> 6392017, 2915918, 37253956, 5029196, 3574097, 601723, 968...
+$ pop_estimataes_base <int> 6392310, 2915958, 37254503, 5029324, 3574096, 601767, 968...
+$ pop_2010            <int> 6411999, 2922297, 37336011, 5048575, 3579345, 605210, 971...
+$ pop_2011            <int> 6472867, 2938430, 37701901, 5119661, 3590537, 620427, 981...
+$ pop_2012            <int> 6556236, 2949300, 38062780, 5191709, 3594362, 635040, 991...
+$ pop_2013            <int> 6634997, 2958765, 38431393, 5272086, 3599341, 649111, 999...
+$ pop_2014            <int> 6731484, 2966369, 38802500, 5355866, 3596677, 658893, 100...
+$ geometry            <list> [-112.53859, -112.53454, -112.36895, -112.35769, -111.41...#' }
+
+A reference GeoJSON file is provided in the following location (i.e. you can use
+it in any mapping program):
+
+\preformatted{
+system.file("extdata/composite_us_states.geojson.gz", package="albersusa")
+}
+}
+\examples{
+library(sf)
+
+plot(usa_sf())
+plot(usa_sf("laea"))
+}
+