# [R] algorithm -- generating combinations

Warnes, Gregory R gregory_r_warnes at groton.pfizer.com
Sat May 4 16:06:17 CEST 2002

```It sounds like you want to do 'all possible subsets' regression.  There are
a couple of packages that address this, leaps and subsets.  See
http://cran.r-project.org/src/contrib/PACKAGES.html

If you really want to examine all possible subsets yourself, you can use the
te combinations() from the package gregmisc to compute all the combinations
of the column names.

-Greg

> -----Original Message-----
> From: Lukas Kubin [mailto:lukas.kubin at permonik.com]
> Sent: Saturday, May 04, 2002 4:15 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] algorithm -- generating combinations
>
>
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> I would like to code a script which processess all possible
> combinations
> of matrix columns. The purpose of such operation is to
> automatically find
> best combination of factors (not those factors in mean of R, but
> explaining factors -- independent variables) received from lm(). The
> independent variables are present in columns of the matrix.
> I am not a skilled programmer and I would like to ask someone
> to help me
> create an algorithm generating the factors' combination so
> that I can work
> with them further. What I need is: Let's say I have 3 matrix
> columns --
> x1, x2, x3. The algorithm returns combinations x1 x2 x3; x1
> x2; x2 x3; x1
> x3; x1; x2; x3. It should also allow to limit the resulting set of
> variables to contain at least a given number of items. For
> example: limit
> is 2, algorithm returns x1 x2 x3; x1 x2; x2 x3 and x1 x3.
> Which format should be the returned result? A vector? I will
> need to use
> it way like: matrix[, c(1, 2, 3)] for a returned set x1 x2 x3.
>
> I am almost sure all I am looking for has someone already done. I will
> appreciate any help.
> Thank you.
>
> lukas
>
> - --
> Lukas Kubin
> lukas.kubin at permonik.com
> phone: 00420603836180
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```