Outlined text with ggplot2

Question

I\'d like to know if there is a way to draw \"outlined text\" with ggplot2, for example black text with a small white border, in order to make it easily readable on backgrou

Answer 1

Not ideal or very flexible but you can get the effect by drawing bold mono text, then standard mono text on top.

I've used a green panel background to simulate the map.

d <- diamonds[sample(nrow(diamonds), 10), ]

(p <- ggplot(d, aes(carat, price)) +
  geom_text(
    aes(label = cut, family = "mono", fontface = "bold"), 
    size = 12, 
    colour = "black"
  ) +
  geom_text(
    aes(label = cut, family = "mono"), 
    size = 12, 
    colour = "white"
  ) +
  opts(panel.background = theme_rect(fill = "green"))
)

Answer 2

Much simplier solution is to use shadowtext library and use geom_shadowtext instead of geom_text

Answer 3

Here is an approach that implements the general idea from the shadowtext function in the TeachingDemos package. The code for the middle part could be wrapped into a function to simplify some things. The example is blatantly stolen from Richie Cotton's answer:

d <- diamonds[sample(nrow(diamonds), 10), ]  


p <- ggplot(d, aes(carat, price) ) 
theta <- seq(pi/8, 2*pi, length.out=16)
xo <- diff(range(d$carat))/200
yo <- diff(range(d$price))/200
for(i in theta) {
    p <- p + geom_text( 
        bquote(aes(x=carat+.(cos(i)*xo),y=price+.(sin(i)*yo),label=cut)), 
                    size=12, colour='black' )
}
p <- p + geom_text( aes(label=cut), size=12, colour='white' )
p <- p + opts( panel.background=theme_rect(fill='green' ) )
print(p)

Answer 4

The accepted answer by Greg Snow doesn't work anymore with ggplot2@2.2.1 because of the call of aes instead of aes_q.

Use

for(i in theta) {
  p <- p + geom_text( 
    aes_q(x = bquote(carat+.(cos(i)*xo)),
          y = bquote(price+.(sin(i)*yo)),
          label = ~cut), 
    size=12, colour='black' )
}

instead.