R help - Jan 2006 - all possible combinations of list elements

I have a list as follows

P <- list(A  = c("CS", "CX"),
          B  = 1:4,
          Y  = c(4, 9))

I now would like to prepare a new list where the rows of the new list
provide all possible combinations of the elements in the orginal list.
Thus, the result should be the following

CS	1	4
CS	1	9
CS	2	4
CS	2	9
CS	3	4
CS	3	9
CS	4	4
CS	4	9
CX	1	4
CX	1	9
CX	2	4
CX	2	9
CX	3	4
CX	3	9
CX	4	4
CX	4	9

Is there a simple routine in R to create this list of all possible
combinations? The routine will be part of a function with the list "P"
as an input. "P" will not always have the same number of elements and
each element in the list "P" may have different numbers of values.

Thanks,
Eberhard Morgenroth
____________________________________________________________________ 
Eberhard Morgenroth, Assistant Professor of Environmental Engineering 
University of Illinois at Urbana-Champaign 
3219 Newmark Civil Engineering Laboratory, MC-250 
205 North Mathews Avenue, Urbana, IL 61801, USA 
Email: emorgenr at uiuc.edu 
http://cee.uiuc.edu/research/morgenroth

On Tue, 2006-01-03 at 18:57 -0600, Eberhard F Morgenroth
wrote:
> I have a list as follows
> 
> P <- list(A  = c("CS", "CX"),
>           B  = 1:4,
>           Y  = c(4, 9))
> 
> I now would like to prepare a new list where the rows of the new list
> provide all possible combinations of the elements in the orginal list.
> Thus, the result should be the following
> 
> CS	1	4
> CS	1	9
> CS	2	4
> CS	2	9
> CS	3	4
> CS	3	9
> CS	4	4
> CS	4	9
> CX	1	4
> CX	1	9
> CX	2	4
> CX	2	9
> CX	3	4
> CX	3	9
> CX	4	4
> CX	4	9
> 
> Is there a simple routine in R to create this list of all possible
> combinations? The routine will be part of a function with the list
"P"
> as an input. "P" will not always have the same number of elements
and
> each element in the list "P" may have different numbers of
values.
See ?expand.grid
> expand.grid(P)
    A B Y
1  CS 1 4
2  CX 1 4
3  CS 2 4
4  CX 2 4
5  CS 3 4
6  CX 3 4
7  CS 4 4
8  CX 4 4
9  CS 1 9
10 CX 1 9
11 CS 2 9
12 CX 2 9
13 CS 3 9
14 CX 3 9
15 CS 4 9
16 CX 4 9

HTH,

Marc Schwartz