r - Draw a chronological timeline with ggplot2

Question

I have data like

data = as.data.frame(  rbind(   c("1492", "Columbus sailed the ocean blue"),
                                c("1976", "Americans listened to Styx"),
                                c("2008", "financial meltdown. great.")
                                ))

and I want to build a plot in ggplot2 that will display an arrow for time aes(x=$V1) and text for aes(label=$V2). It sounded pretty simple until I tried to draw it.

update: I didn't write it but you need to do as.Date("1492", format="%Y") to reproduce correctly.

NB: Solutions given below only deal with events that occur at a specific date -- not timelines with "periods" or "eras".

Answer 1

Sometimes the simplest graphics are the most difficult to create in ggplot2, but it is possible (and pretty).

data =data.frame( V1=c(1492,1976,2008),V2=c("Columbus sailed the ocean blue","Americans listened to Styx","financial meltdown"),disloc=c(-1,1,-.5))
dev.new()
ggplot() +
    geom_segment(aes(x = V1,y = disloc,xend = V1),data=data,yend = 0) +
    geom_segment(aes(x = 900,y = 0,xend = 2050,yend = 0),data=data,arrow = arrow(length = unit(x = 0.2,units = 'cm'),type = 'closed')) +
    geom_text(aes(x = V1,y = disloc,label = V2),data=data,hjust = 1.0,vjust = 1.0,parse = FALSE) +
    geom_point(aes(x = V1,y = disloc),data=data) +
    scale_x_continuous(breaks = c(1492,1976,2008),labels = c("1492","1976","2008")) +
    theme_bw() +
    opts(axis.text.x = theme_text(size = 12.0,angle = 90.0),axis.text.y = theme_blank(),axis.ticks = theme_blank(),axis.title.x = theme_blank(),axis.title.y = theme_blank())

Note: this graphic was produced entirely in the ggplot2 Plot Builder in Deducer