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Reproduce Minard's March on Moscow Graphic using ggplot2
#' # Reproduce Minard's March on Moscow Graphic using ggplot2
#' This gist extends the examples given in the HistData package. It explicitly
#' shows the construction of the plot as layers, and adds the plot of temperature
#' vs. longitude below the plot of troop strength.
#' ## Load data and required packages
data(Minard.troops, package="HistData")
data(Minard.cities, package="HistData")
data(Minard.temp, package="HistData")
require(ggplot2)
require(scales)
require(gridExtra)
#' ## plot path of troops, and another layer for city names
plot_troops <- ggplot(Minard.troops, aes(long, lat)) +
geom_path(aes(size = survivors, colour = direction, group = group),
lineend = "round", linejoin = "round")
plot_cities <- geom_text(aes(label = city), size = 4, data = Minard.cities)
#' ## Combine these, and add scale information, labels, etc.
#' Set the x-axis limits for longitude explicitly, to coincide with those for temperature
breaks <- c(1, 2, 3) * 10^5
plot_minard <- plot_troops + plot_cities +
scale_size("Survivors", range = c(1, 10),
breaks = breaks, labels = scales::comma(breaks)) +
scale_color_manual("Direction",
values = c("grey50", "red"),
labels=c("Advance", "Retreat")) +
coord_cartesian(xlim = c(24, 38)) +
xlab(NULL) +
ylab("Latitude") +
ggtitle("Napoleon's March on Moscow") +
theme_bw() +
theme(legend.position=c(.8, .2), legend.box="horizontal")
#' ## plot temperature vs. longitude, with labels for dates
plot_temp <- ggplot(Minard.temp, aes(long, temp)) +
geom_path(color="grey", size=1.5) +
geom_point(size=2) +
geom_text(aes(label=date)) +
xlab("Longitude") + ylab("Temperature") +
coord_cartesian(xlim = c(24, 38)) +
theme_bw()
#' The plot works best if we re-scale the plot window to an aspect ratio of ~ 2 x 1
windows(width=10, height=5)
#' Combine the two plots into one
grid.arrange(plot_minard, plot_temp, nrow=2, heights=c(3,1))
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