8 Highlight a range of x-values

• Dale Barr (March 23, 2020)

Sometimes you want to highlight a particular range of values; for example, a particular period of time in a time series.

The code below is used to create the following plot.

Figure 8.1: A time series with x = 40-60 highlighted

library("tidyverse")

## make up some example data
exdata <- tibble(x = rep(1:100, 2),
                 series = rep(1:2, each = 100),
                 y = rnorm(200) + rep(c(30, 50), each = 100))

## region we want to highlight
regions <- tibble(x1 = 40, x2 = 60, y1 = -Inf, y2 = +Inf)

ggplot(exdata, aes(x, y)) +
  geom_rect(data = regions,
            inherit.aes = FALSE,
            mapping = aes(xmin = x1, xmax = x2,
                          ymin = y1, ymax = y2),
            color = "transparent",
            fill = "blue",
            alpha = .2) +
  geom_line(aes(group = series))