[R] Basic plot question: Figure 1.1 Pinheiro & Bates

[David Afshartous]

All,
Sorry for overly simplistic question, but I can't seem to remember how to
create the basic plot shown in Figure 1.1 of Pinheiro & Bates (2004; p.4).
The y-axis delineates a factor (Rail) while the x-axis displays the
distribution of a continuous variable (time) according to each level of the
factor.  Didn't see it in archives but perhaps I'm not searching on correct
key words, any help appreciated,
David


> library("nlme")
> Rail
Grouped Data: travel ~ 1 | Rail
   Rail travel
1     1     55
2     1     53
3     1     54
4     2     26
5     2     37
6     2     32
7     3     78
8     3     91
9     3     85
10    4     92
11    4    100
12    4     96
13    5     49
14    5     51
15    5     50
16    6     80
17    6     85
18    6     83