the puma of my childhood

puma of my childhood.R

# install mapping packages
install.packages( c( 'sp' , 'rgdal' ) )

# load necessary libraries
require(sp)
require(rgdal)

# create a temporary file and directory
tf <- tempfile() ; td <- tempdir()

# download the census state shape files
download.file(
  "http://www.census.gov/geo/cob/bdy/st/st00shp/st24_d00_shp.zip" ,
	tf , 
	mode = 'wb'
)

# extract all files to the temporary directory
files <- unzip( tf , exdir = td )

# find the shape file
sf <- files[ grepl( 'shp' , files ) ]

# read the shape file
state <- readOGR( sf , "st24_d00" )

# download the maryland public use microdata area (puma) shape file
download.file(
	"http://www.census.gov/geo/cob/bdy/pu/p500shp/p524_d00_shp.zip" ,
	tf , 
	mode = 'wb'
)

# extract all files to the temporary directory
files <- unzip( tf , exdir = td )

# find the shape file
sf <- files[ grepl( 'shp' , files ) ]

# read both shape files
puma <- readOGR( sf , "p524_d00" )

# plot the state boundary
plot( state )

# plot just one puma
plot( puma[ puma$PUMA5 == '01004' , ] , col = 'blue' , add = TRUE )