library(tigris)
library(ggplot2)
library(ggthemes)
library(rgeos)
library(sp)
roads <- roads("Maine", "031")
# for ggplot, we need to simplify the lines otherwise it'll take
# forever to plot. however, gSimplify whacks the SpatialLinesDataFrame
# so we need to re-bind the data from the original object to it so
# we can use "fortify"
roads_simp <- gSimplify(roads, tol=1/200, topologyPreserve=TRUE)
roads_simp <- SpatialLinesDataFrame(roads_simp, roads@data)
roads_map <- fortify(roads_simp) # this takes a bit
gg <- ggplot()
gg <- gg + geom_map(data=roads_map, map=roads_map,
aes(x=long, y=lat, map_id=id),
color="black", fill="white", size=0.25)
gg <- gg + coord_map()
gg <- gg + theme_map()
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