Add function to load FIPS data (#3)

* Added `fips_data` function to load FIPS data from included csv files
* Provides cleaner way to load FIPS data in `usmap` package without
loading `extdata` file

See
[pdil/usmap#58](pdil/usmap#72 (comment))

NAMESPACE

@@ -1,4 +1,5 @@
 # Generated by roxygen2: do not edit by hand
 
 export(centroid_labels)
+export(fips_data)
 export(us_map)

NEWS.md

@@ -1,6 +1,8 @@
 # usmapdata 0.1.1.9999
 
-
+* Add `fips_data` function to load raw FIPS data from included csv files.
+    * `fips_data()`, `fips_data("state")`, or `fips_data("states")` load state FIPS codes
+    * `fips_data("county")` or `fips_data("counties")` load county FIPS codes
 
 # usmapdata 0.1.1
 Released Saturday, October 21, 2023.

R/fips-data.R

@@ -0,0 +1,29 @@
+#' Retrieve state and county FIPS codes
+#'
+#' @param regions The region breakdown for the map, can be one of
+#'   (\code{"states"}, \code{"state"}, \code{"counties"}, \code{"county"}).
+#'   The default is \code{"states"}.
+#'
+#' @return A data frame of FIPS codes of the desired \code{regions}.
+#'
+#' @examples
+#' str(fips_data())
+#'
+#' state_fips <- fips_data()
+#' county_fips <- fips_data(regions = "counties")
+#'
+#' @export
+fips_data <- function(regions = c("states", "state", "counties", "county")) {
+  regions_ <- match.arg(regions)
+
+  if (regions_ == "state" || regions_ == "states")
+    utils::read.csv(
+      system.file("extdata", "state_fips.csv", package = "usmapdata"),
+      colClasses = rep("character", 3), stringsAsFactors = FALSE
+    )
+  else if (regions_ == "county" || regions_ == "counties")
+    utils::read.csv(
+      system.file("extdata", "county_fips.csv", package = "usmapdata"),
+      colClasses = rep("character", 4), stringsAsFactors = FALSE
+    )
+}

tests/testthat/test-fips-data.R

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+context("Loading FIPS data")
+
+test_that("state FIPS codes load correctly", {
+  fips <- fips_data()
+  state_fips <- fips_data("state")
+  states_fips <- fips_data("states")
+
+  expect_identical(fips, state_fips)
+  expect_identical(fips, states_fips)
+  expect_identical(state_fips, states_fips)
+
+  expect_equal(length(fips), 3)
+  expect_equal(length(fips[, 1]), 51)
+
+  expect_equal(fips[1, "abbr"], "AK")
+  expect_equal(fips[1, "fips"], "02")
+  expect_equal(fips[1, "full"], "Alaska")
+
+  expect_equal(fips[51, "abbr"], "WY")
+  expect_equal(fips[51, "fips"], "56")
+  expect_equal(fips[51, "full"], "Wyoming")
+})
+
+test_that("county FIPS codes load correctly", {
+  county_fips <- fips_data("county")
+  counties_fips <- fips_data("counties")
+
+  expect_identical(county_fips, counties_fips)
+
+  expect_equal(length(county_fips), 4)
+  expect_equal(length(county_fips[, 1]), 3236)
+
+  expect_equal(county_fips[1, "full"], "Alaska")
+  expect_equal(county_fips[1, "abbr"], "AK")
+  expect_equal(county_fips[1, "county"], "Aleutians West Census Area")
+  expect_equal(county_fips[1, "fips"], "02016")
+
+  expect_equal(county_fips[3236, "full"], "Wyoming")
+  expect_equal(county_fips[3236, "abbr"], "WY")
+  expect_equal(county_fips[3236, "county"], "Washakie County")
+  expect_equal(county_fips[3236, "fips"], "56043")
+})