Drawing an interval on the graph using vertical line in R ?

Question

install.packages("devtools")
library(devtools)
devtools::install_github("google/CausalImpact")
library(CausalImpact)

set.seed(1)
x1 <- 100 + arima.sim(model = list(ar = 0.999), n = 100)
y <- 1.2 * x1 + rnorm(100)
y[71:100] <- y[71:100] + 10
data <- cbind(y, x1)
pre.period <- c(1, 70)
post.period <- c(71, 100)
impact <- CausalImpact(data, pre.period, post.period)
plot(impact, "cumulative")

Say i want the graph to show an interval from 71-100 with the x scales starting at 1 from the first dotted line any ideas on how to do this? Does anyone have any idea how to add a second vertical dotted line depicting an interval on the graph? Thanks.

Answer 1

You can use abline() to add lines to a graph, with the argument v = 70 setting a vertical line at x = 70. I'm not sure how to restart the x-scale from that point however - it doesn't seem like something that would be possible but perhaps someone else knows how.

Answer 2

You can reset the axes using this.

In your initial plot command, set xaxt = "n" This ensures that the plot function does not mark the axes.

You can then draw the abline(v=70) as mentioned above.

Then use axis(1,at=seq(60,80,by=1),las=1) 1 stands for x-axis and in the at attribute, mention the x limits you want. I've put in 60 to 80 as an example.