Migue Migue - 16 days ago 8
R Question

How to add a ggplot2 subtitle with different size and colour?

I'm using ggplot2 to improve precipitation barplots.

Here's a reproducible example of what I want to achieve:

library(ggplot2)
library(gridExtra)
secu <- seq(1, 16, by=2)
melt.d <- data.frame(y=secu, x=LETTERS[1:8])
m <- ggplot(melt.d, aes(x=x, y=y)) + geom_bar(fill="darkblue") + labs(x="Weather stations", y="Accumulated Rainfall [mm]") + opts(axis.text.x=theme_text(angle=-45, hjust=0, vjust=1), title=expression("Rainfall"), plot.margin = unit(c(1.5, 1, 1, 1), "cm"), plot.title = theme_text(size = 25, face = "bold", colour = "black", vjust = 5))
z <- arrangeGrob(m, sub = textGrob("Location", x = 0, hjust = -3.5, vjust = -33, gp = gpar(fontsize = 18, col = "gray40"))) #Or guessing x and y with just option
z


I don't know how to avoid using guessing numbers on hjust and vjust on ggplot2? Is there a better way to put a subtitle (not just using \n, but a subtitle with different text color and size)?

I need to be able to use with ggsave to have a pdf file.

Here are two related questions:

Add a footnote citation outside of plot area in R?

How can I add a subtitle and change the font size of ggplot plots in R?

Thanks for any help.

Answer

Ignore this answer ggplot2 version 2.2.0 has title and subtitle functionality. See @hrbrmstr's answer here.

You could use nested atop functions inside an expression to get different sizes.

EDIT Updated code for ggplot2 0.9.3

m <-  ggplot(melt.d, aes(x=x, y=y)) + 
     geom_bar(fill="darkblue", stat = "identity") + 
     labs(x="Weather    stations", y="Accumulated Rainfall [mm]") + 
     ggtitle(expression(atop("Rainfall", atop(italic("Location"), "")))) +
     theme(axis.text.x = element_text(angle=-45, hjust=0, vjust=1), 
     #plot.margin = unit(c(1.5, 1, 1, 1), "cm"), 
     plot.title = element_text(size = 25, face = "bold", colour = "black", vjust = -1))

enter image description here

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