RE: [R] 'combinations' in gtools and stack overflow

[Prof Brian Ripley]

On Mon, 14 Feb 2005, Warnes, Gregory R wrote:
The documentation for 'combinations' explicitly describes this problem:
Not so: this is misinformation send in reply to correct and helpful 
comments.

 Details:
    Caution: The number of combinations and permutations increases
    rapidly with 'n' and 'r'!.
    To use values of 'n' above about 45, you will need to increase R's
    recursion limit.  See the 'expression' argument to the 'options'
    command for details on how to do this.
and gives an example of the solution:
    # To use large 'n', you need to change the default recusion limit
    options(expressions=1e5)
    cmat <- combinations(300,2)
    dim(cmat) # 44850 by 2
Let me repeat for you what he said he did:
library(gtools)
options(expressions=1e5)
combinations(500, 3, 1:500)
# or combinations(400, 2, 1:400)
Error: protect(): stack overflow
Do you notice the second line there this time around?
The message is not about the number of expressions, but about the 
sizd of the protect stack.

R --max-ppsize=50000
allows combinations(400, 2, 1:400) to work, as I correctly suggested.
-Greg
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Prof
Brian Ripley
Sent: Monday, February 14, 2005 10:23 AM
To: Ho-Joon Lee
Cc: r-help@stat.math.ethz.ch
Subject: Re: [R] 'combinations' in gtools and stack overflow
On Mon, 14 Feb 2005, Ho-Joon Lee wrote:
Dear R-users,
Let me ask about the 'stack overflow' error which I got
when I used the
function 'combinations' in "gtools".
The following is what I did:
---------
library(gtools)
options(expressions=1e5)
combinations(500, 3, 1:500)
# or combinations(400, 2, 1:400)
Error: protect(): stack overflow
---------
How can I overcome this error? Is there perhaps any other
function to do this
more efficiently?
R --help lists a flag that you can use to increase the size
of the protect
stack.  It is also described in `An Introduction to R'.
--
Brian D. Ripley,                  [EMAIL PROTECTED]
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595
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--
Brian D. Ripley,                  [EMAIL PROTECTED]
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595
______________________________________________
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html