Electoral map

electoral_map.R

doInstall <- TRUE  # Change to FALSE if you don't want packages installed.
toInstall <- c("maps", "ggplot2", "RColorBrewer")
if(doInstall){install.packages(toInstall, repos = "http://cran.r-project.org")}
lapply(toInstall, library, character.only = TRUE)

new_theme_empty <- theme_bw()  # Create our own, mostly blank, theme
new_theme_empty$line <- element_blank()
new_theme_empty$rect <- element_blank()
new_theme_empty$strip.text <- element_blank()
new_theme_empty$axis.text <- element_blank()
new_theme_empty$axis.title <- element_blank()
new_theme_empty$plot.margin <- structure(c(0, 0, -1, -1), unit = "lines", valid.unit = 3L, class = "unit")

stateShapes <- map("state", plot = FALSE, fill = TRUE)
stateShapes <- fortify(stateShapes)  # Load state shapefiles and convert to a data.frame

uniqueStates <- sort(unique(stateShapes$region))
stateResults <- runif(length(uniqueStates), 0, 100)
names(stateResults) <- uniqueStates  # Romney vote / Obama vote:
stateResults["alabama"] <- 60.7/38.4; stateResults["arizona"] <- 55/43.4; stateResults["arkansas"] <- 60.4/37.0
stateResults["california"] <- 38.5/59.2; stateResults["colorado"] <- 47/50.7; stateResults["connecticut"] <- 40.6/58.3
stateResults["delaware"] <- 40/58.6; stateResults["district of columbia"] <- NA; stateResults["florida"] <- 49.3/49.8  # 7.1/91.4
stateResults["georgia"] <- 53.4/45.4; stateResults["idaho"] <- 65.8/31.5; stateResults["illinois"] <- 41.1/57.3
stateResults["indiana"] <- 54.3/43.8; stateResults["iowa"] <- 46.5/52.1; stateResults["kansas"] <- 59.9/37.9
stateResults["kentucky"] <- 60.5/37.8; stateResults["louisiana"] <- 58.5/39.8; stateResults["maine"] <- 40.3/56.3
stateResults["maryland"] <- 37/61.2; stateResults["massachusetts"] <- 37.5/60.9; stateResults["michigan"] <- 45.5/53.6
stateResults["minnesota"] <- 45.1/52.8; stateResults["mississippi"] <- 55.4/43.6; stateResults["missouri"] <- 53.9/44.3
stateResults["montana"] <- 56.6/41.5; stateResults["nebraska"] <- 60.5/37.8; stateResults["nevada"] <- 45.7/52.3
stateResults["new hampshire"] <- 46.7/52; stateResults["new jersey"] <- 51.0/57.9; stateResults["new mexico"] <- 43/52.9
stateResults["new york"] <- 35.9/62.7; stateResults["north carolina"] <- 50.6/48.4; stateResults["north dakota"] <- 58.7/38.9
stateResults["ohio"] <- 48.2/50.1; stateResults["oklahoma"] <- 66.8/33.2; stateResults["oregon"] <- 44.1/53.3
stateResults["pennsylvania"] <- 46.8/51.9; stateResults["rhode island"] <- 35.2/63.1; stateResults["south carolina"] <- 55/43.7
stateResults["south dakota"] <- 57.9/39.9; stateResults["tennessee"] <- 59.5/39; stateResults["texas"] <- 57.2/41.4
stateResults["utah"] <- 72.7/24.9; stateResults["vermont"] <- 31.2/67.1; stateResults["virginia"] <- 47.8/50.8
stateResults["washington"] <- 42.8/55.2; stateResults["west virginia"] <- 42.8/55.2; stateResults["wisconsin"] <- 62.3/35.5
stateResults["wyoming"] <- 69.3/28

stateResults <- 100 * stateResults / (stateResults + 1)  # Convert to proportion of the two-party vote

stateShapes$repVote <- by(stateResults, uniqueStates, mean)[stateShapes$region]  # Add results to shapefile frame

myPalette <- colorRampPalette(rev(brewer.pal(11, "RdYlBu")))  # Make a custom color palette
normalize <- function(x){  (x - min(x, na.rm = T)) / (max(x, na.rm = T) - min(x, na.rm = T))  }
myPalette <- colorRampPalette(myPalette(1000)[round(1000 * normalize(qbeta(1:999 /1000, 1/3, 1/3)))])
myPalette <- myPalette(1000)#[0:700]  # Not needed, if you leave out DC, which really skews the palette

mapPlot <- ggplot(stateShapes,
                  aes(x = long, y = lat, group = group,
                      fill = repVote))
mapPlot <- mapPlot + geom_polygon(colour = "BLACK")
mapPlot <- mapPlot + coord_map(project="conic", lat0 = 30)
mapPlot <- mapPlot + new_theme_empty
mapPlot <- mapPlot + scale_fill_gradientn("Romney Prop.\nof the 2PV",
                                          colours = myPalette)
mapPlot <- mapPlot + ggtitle("2012 Election Returns by State")
print(mapPlot)

Very nice example. You may want to add the mapproj package to the list of dependencies, as it's required for the "project="conic"" option in ggplot2. :)

Hi! I am working on a project in one of my classes that requires the use of R and my group and I are trying to plot an electoral map on the 2012 US elections and this is useful but where do you get the mapproj package? When I try your code it tells me I do not have this package! This was posted a while ago but if you could answer that would be amazing!