Drawing a timeline with ggplot2
Recently I wanted to create a timeline for a presentation the next day and came up with this code chunk. I’m certainly not recommending it as the prettiest or quickest way to make a timeline, but I couldn’t get Dean Attali’s timevis to work in an ioslides presentation. I also didn’t know about timeline, which I’ll try in the future.
The idea is pretty simple - it’s basically a standard use of geom_label, and then you remove unnecessary axes, background elements and so on.1 The thing that really makes this work is the str_wrap function from the stringr package. If you have a table of years and event descriptions, you can pass the event descriptions through str_wrap, so the “plotted” text will be wrapped nicely.
years = c(1998L, 2001L, 2004L, 2006L, 2006L, 2009L)
events = data_frame(event = c("Impeachment of Bill Clinton",
"George W. Bush takes office",
"Kerry runs against Bush",
"Something happens",
"Another thing happens",
"Barack Obama takes office"),
year = c(1998L, 2001L, 2004L - 0.2, 2006L, 2006L, 2009L),
y = 1,
vpos = c(1.2, 1.2, 1.2, 1.5, 1.2, 1.2))
events %<>% mutate(event = str_wrap(event, 15))
events %>%
ggplot(aes(year, y)) + geom_point() +
geom_line() + geom_label(aes(x = year, y = vpos, label = event), size = 5) +
theme(
panel.border = element_blank(), panel.grid.major = element_blank(),
panel.grid.minor = element_blank(), axis.line = element_line(colour = "black"),
axis.line.y = element_blank(), axis.text.y = element_blank(), axis.title.y = element_blank()) +
coord_cartesian(ylim = c(0, 2), xlim = c(1997, 2010)) +
scale_x_continuous(breaks = c(1998L, 2001L, 2004L, 2006L, 2009L)) +
geom_segment(aes(xend = year, y = 0, yend = 1)) +
labs(x = "Year", title = "Example with Political Events")
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For the sake proper attribution, I got some of the code for removing graph elements from Stack Overflow but can’t find that question anymore. ↩
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