R help - Aug 2006 - plot question

Hi everyone,

I have what may appear to be a newbie question, but I have looked 
everywhere I can think to look and I cannot find an answer. On page 35 
of "An Introduction to R" the following command appears: 
plot(ecdf(eruptions), do.points=FALSE, verticals=TRUE). What is the 
do.points argument? I know what it does (suppresses printing of the 
points) but where can I find help on it? I want to be able to explain it 
fully to my students.

Thanks for your help,
Cathy

-- 
Dr. Cathy Carter
Department of Geography
University of Maryland
1111A LeFrak Hall
301.405.4620

Take a look at ?plot.stepfun.

'ecdf()' returns an object of class "ecdf" inheriting from
class "stepfun" and
'plot.ecdf()' calls 'plot.stepfun'.

-roger

Catherine Carter wrote:
> Hi everyone,
> 
> I have what may appear to be a newbie question, but I have looked 
> everywhere I can think to look and I cannot find an answer. On page 35 
> of "An Introduction to R" the following command appears: 
> plot(ecdf(eruptions), do.points=FALSE, verticals=TRUE). What is the 
> do.points argument? I know what it does (suppresses printing of the 
> points) but where can I find help on it? I want to be able to explain it 
> fully to my students.
> 
> Thanks for your help,
> Cathy
> 
-- 
Roger D. Peng  |  http://www.biostat.jhsph.edu/~rpeng/

On Fri, 2006-08-25 at 09:08 -0400, Catherine Carter
wrote:
> Hi everyone,
> 
> I have what may appear to be a newbie question, but I have looked 
> everywhere I can think to look and I cannot find an answer. On page 35 
> of "An Introduction to R" the following command appears: 
> plot(ecdf(eruptions), do.points=FALSE, verticals=TRUE). What is the 
> do.points argument? I know what it does (suppresses printing of the 
> points) but where can I find help on it? I want to be able to explain it 
> fully to my students.
> 
> Thanks for your help,
> Cathy
A couple of options:

1. If you are aware of how R uses "method dispatch", then you might
know
that the plot() function is a generic method and that plot.ecdf() is the
specific method that is called when the initial argument is of class
"ecdf", as is the case above. 

Thus, using ?plot.ecdf will get you to the help page, where there is a
notation in the Arguments section that the '...' arguments are then
passed to plot.stepfun(). 'do.points' is passed in this fashion, so
using ?plot.stepfun will then get you to the help page where 'do.points'
is defined as:

  logical; if true, also draw points at the (xlim restricted)
  knot locations.


2. Using:

  RSiteSearch("do.points", restrict = "functions")

will search the online function documentation, bringing up a browser
window, where the first link gets you to ?plot.stepfun.

HTH,

Marc Schwartz