Position ggplot text in each corner

Question

I\'ve got a scatter plot with a horizontal and a vertical line, which depict thresholds values, and therefore they divide the plot into four quadrants. I\'d like to label th

Answer 1

This example uses the Inf & -Inf values to position the text at the corners and then hjust and vjust arguments in the geom_text to position the text inside the plot. Use the hjustvar and vjustvar to position them further into or outside the plot.

As mentioned by @baptiste it's best to use a new data set for the annotations

df <- data.frame(x2=rnorm(100),y2=rnorm(100));library(ggplot2)

annotations <- data.frame(
        xpos = c(-Inf,-Inf,Inf,Inf),
        ypos =  c(-Inf, Inf,-Inf,Inf),
        annotateText = c("Bottom Left (h0,v0)","Top Left (h0,v1)"
                        ,"Bottom Right h1,v0","Top Right h1,v1"),
        hjustvar = c(0,0,1,1) ,
        vjustvar = c(0,1,0,1)) #<- adjust


  ggplot(df, aes(x2, y2)) + geom_point()+
            geom_text(data=annotations,aes(x=xpos,y=ypos,hjust=hjustvar,vjust=vjustvar,label=annotateText))

If we wanted to change any of the text positions, we would adjust the horizontal positions with hjustvar and the vertical positions with vjustvar.

# How To Adjust positions (away from corners)
annotations$hjustvar<-c(0,  -1.5,  1,  2.5)  # higher values = right, lower values = left 
annotations$vjustvar<-c(0,1,0,1) # higher values = up, lower values = down 

ggplot(df, aes(x2, y2)) + geom_point()+
        geom_text(data = annotations, aes(x=xpos,y=ypos,hjust=hjustvar,
                                          vjust=vjustvar,label=annotateText))

Hope this works!

Answer 2

when adding annotations, make sure to give a new data set, or to use annotate, otherwise multiple labels will be superimposed giving a jagged look. Here's a minimal change from the other answer,

df <- data.frame(x2=rnorm(100),y2=rnorm(100))
library(ggplot2)

annotations <- data.frame(
   xpos = c(-Inf,-Inf,Inf,Inf),
   ypos =  c(-Inf, Inf,-Inf,Inf),
   annotateText = c("Text","tExt","teXt","texT"),
   hjustvar = c(0,0,1,1) ,
   vjustvar = c(0,1.0,0,1))


  ggplot(df, aes(x2, y2)) + geom_point()+
  geom_text(data = annotations, aes(x=xpos,y=ypos,hjust=hjustvar,
                vjust=vjustvar,label=annotateText))