ggplot2 annotate layer position in R

Question

In my plot I have both legends and text annotations. For legends, I can specify

legend.justification=c(1,0), legend.position=c(1,0)

to locate the position relative to the plotting region (e.g. topright, bottomleft). However, when I put an annotate layer (http://docs.ggplot2.org/0.9.3.1/annotate.html), it seems that I can only specify the coordinates of the text

annotate("text", x = 8e-7, y = 1e-5, label=data.note, size = 5)

instead of the position of the plotting region (I want to put the text in the bottomleft corner). The length of the text (label) may vary for different plots. Is there a way to achieve this? Thanks!

Answer 1

Is this what you're looking for??

set.seed(1)
df <- data.frame(x=rnorm(100),y=rnorm(100))
ggplot(df, aes(x,y)) +geom_point()+
  annotate("text",x=min(df$x),y=min(df$y),hjust=.2,label="Text annotation")

There will probably be a bit of experimentation with hjust=... needed to get this exactly at the bottom left.

Answer 2

You can use the fact that -Inf and Inf will get mapped to the extremes of the position scales without extending them to place it in the bottom left corner. hjust and vjust are needed to make the reference point the lower left corner of your text. [using jlhoward's mock data.]

set.seed(1)
df <- data.frame(x=rnorm(100),y=rnorm(100))

ggplot(df, aes(x,y)) +geom_point()+
  annotate("text",x=-Inf,y=-Inf,hjust=0,vjust=0,label="Text annotation")