CODEWITHSUNDEEP
rggplot2
Elizabeth
Elizabeth

Reputation: 6561

Highlighting particular regions of a scatterplot in a ggplot

I need to discuss a scatter plot and would like to refer to particular regions of the plot. Is there any way to 'highlight' particular sections of the plot? Perhaps with boxes and labels as below?

set.seed(1410)
dsmall<-diamonds[sample(nrow(diamonds), 100), ]
df<-data.frame("x"=dsmall$carat, "y"=dsmall$price)

p <-ggplot(df, aes(x, y)) 
p <- p + geom_point(alpha=2/10, shape=21, fill="blue", colour="black", size=5)

enter image description here

Upvotes: 10

Views: 2710

Answers (1)

Andrie
Andrie

Reputation: 179428

For a single region, it's easiest to use annotate, first with rect, then text:

p + annotate("rect", xmin=1.5, xmax=2.5, ymin=12500, ymax= 18000, 
             fill=NA, colour="red") +
    annotate("text", x=1.75, y=17000, label="Region A", size=8)

enter image description here

For multiple regions, you can put the data into a data frame and use geom_text and geom_rect:

regions <- data.frame(
  xmin=c(1.5, 1, 0),
  xmax=c(2.5, 2, 1),
  ymin=c(12500, 5000, 0),
  ymax=c(17500, 12500, 5000),
  x   =c(2, 1.5, 0.5),
  y   =c(15000, 7500, 2500),
  lab = paste("Region", LETTERS[1:3])
)

p + 
  geom_rect(data=regions, aes(xmin=xmin, xmax=xmax, ymin=ymin, ymax=ymax), 
            fill=NA, colour="red") +
  geom_text(data=regions, aes(x=x, y=y, label=lab))

enter image description here

Upvotes: 15

Related Questions