Visualobesity4.R

#Generate County map with a few var of interest
percent_map <- function(var, color, legend.title, min = 0, max = 100, name = "") {
    # generate vector of fill colors for map
    shades <- colorRampPalette(c("white", color))(100)
    # constrain gradient to percents that occur between min and max
    var <- pmax(var, min)
    var <- pmin(var, max)
    percents <- as.integer(cut(var, 100,
                               include.lowest = TRUE, ordered = TRUE))
    fills <- shades[percents]
    
    # plot choropleth map
    map("county", fill = TRUE, col = fills, resolution = 0,
        lty = 0, projection = "polyconic",
        myborder = 0, mar = c(0,0,0,0), width = 5, height =4)
    
    # overlay state borders
    map("state", col = "black", fill = FALSE, add = TRUE,
        lty = 1, lwd = 1, projection = "polyconic",
        myborder = 0, mar = c(0,0,0,0), width = 5, height =4)
    title(name)
    
    # add a legend
    inc <- (max - min) / 4
    legend.text <- c(paste0(min, " % or less"),
                     paste0(min + inc, " %"),
                     paste0(min + 2 * inc, " %"),
                     paste0(min + 3 * inc, " %"),
                     paste0(max, " % or more"))
    legend("right",
           legend = legend.text,
           text.font = 12,
           fill = shades[c(1, 25, 50, 75, 100)],
           title = legend.title,
           cex = 1.1)
}