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64 lines
2.3 KiB
64 lines
2.3 KiB
#' Retrieve a U.S. county composite map, optionally with a projection
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#'
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#' The \code{proj} parameter is intende to simplify usage for those using base
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#' plotting. If anything but \code{longlat} is specified the composite map
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#' will be pre-projected to those
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#'
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#' This is what's in the SPDF \code{@data} slot:
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#'
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#' \preformatted{
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#' Observations: 3,143
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#' Variables: 9
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#' $ fips (chr) "01001", "01009", "01017", "01021", "01033", "01045", "01051",...
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#' $ state_fips (chr) "01", "01", "01", "01", "01", "01", "01", "01", "01", "01", "0...
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#' $ county_fips (chr) "001", "009", "017", "021", "033", "045", "051", "065", "079",...
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#' $ name (chr) "Autauga", "Blount", "Chambers", "Chilton", "Colbert", "Dale",...
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#' $ lsad (chr) "County", "County", "County", "County", "County", "County", "C...
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#' $ census_area (dbl) 594.436, 644.776, 596.531, 692.854, 592.619, 561.150, 618.485,...
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#' $ state (chr) "Alabama", "Alabama", "Alabama", "Alabama", "Alabama", "Alabam...
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#' $ iso_3166_2 (chr) "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "AL", "A...
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#' $ population (dbl) 54590, 57466, 34228, 43611, 54451, 50129, 79330, 15750, 34148,...
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#' }
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#'
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#' A reference GeoJSON file isprovided in the following location (i.e. you can use
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#' it in any mapping program):
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#'
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#' \preformatted{
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#' system.file("extdata/composite_us_counties.geojson.gz", package="albersusa")
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#' }
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#'
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#' @param proj if anything but \code{longlat} is specified, the shapefile will
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#' be pre-projected before being returned
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#' @export
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#' @examples
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#' library(sp)
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#'
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#' plot(counties_composite())
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#' plot(counties_composite("laea"))
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counties_composite <- function(proj=c("longlat", "laea", "lcc", "eqdc", "aeqd")) {
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# us <- readOGR(system.file("extdata/composite_us_counties.geojson", package="albersusa"),
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# "OGRGeoJSON",
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# stringsAsFactors=FALSE,
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# verbose=FALSE)
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cty <- readRDS(system.file("extdata/counties.rda", package="albersusa"))
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# saveRDS(cty, "inst/extdata/counties.rda", version = 2)
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proj <- match.arg(proj, c("longlat", "laea", "lcc", "eqdc", "aeqd"))
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if (proj != "longlat") {
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proj <- switch(proj,
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laea=us_laea_proj,
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lcc=us_lcc_proj,
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eqdc=us_eqdc_proj,
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aeqd=us_aeqd_proj)
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cty <- sp::spTransform(cty, sp::CRS(proj))
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}
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cty
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}
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