From: Gavin Simpson <gavin.simpson_at_ucl.ac.uk>

Date: Fri 26 May 2006 - 02:52:00 EST

Date: Fri 26 May 2006 - 02:52:00 EST

On Thu, 2006-05-25 at 09:26 -0700, Peter Lauren wrote:

> I was wondering what would be the best way to put a

*> vertical line on a graph made with plot(). I can get
**> an horizontal line by plotting a vector where every
**> element has the same value but it is not as clear how
**> a vertical line should be done.
**>
**> Thanks very much,
**> Peter.
*

Is this what you want?

set.seed(12345) # reproducible random numbers
datx <- rnorm(100) # some example data

daty <- rnorm(100)

plot(datx, daty) # plot it

abline(v = mean(datx)) # add vertical line at mean of x abline(v = 0.5, col = "red") # same but at x == 0.5 abline(h = mean(daty)) # horizontal lines abline(a = 0, b = 1) # lines of arbitrary intercept and slope

see ?abline

**HTH
**
G

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