how to make a vertical line segment in plot?

Question

I have a plot(x, y) and I want to add a vertical line at x = 2 ONLY from y = 1 to 4. I want to use the lines() function but I'm having trouble limiting the y-range.

What's an easy way to do this?

Answer 1

Here's a simple example of using plot and lines. To draw a line from (2, 1) to (2, 4), you have to provide the x coordinates and y coordinates as (2, 2) and (1, 4):

plot(1:5)
lines(c(2, 2), c(1, 4))