R help - Jan 2014 - how do I extract all possible combinations of rows from a column

Hi,
May be this helps:
library(gtools) 

as.data.frame(t(combinations(5,3,1:5)))
#? V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
#1? 1? 1? 1? 1? 1? 1? 2? 2? 2?? 3
#2? 2? 2? 2? 3? 3? 4? 3? 3? 4?? 4
#3? 3? 4? 5? 4? 5? 5? 4? 5? 5?? 5
A.K.



For a column of data, I need to extract all possible unique 
combinations of 3 rows and combine the results into a data frame (as 
columns). So, for example, if I had a column called "test" that had
five rows (the contents of which were the numbers 1:5) all possible
combinations of 3 rows would be 
1,2,3 
1,2,4 
1,2,5 
1,3,4 
1,3,5 
1,4,5 
2,3,4 
2,4,5 
2,4,5 
3,4,5 

So for this example, R would extract all the combinations shown, and I would get
a data frame that looked like this
1 ? ? 1 ? ? 1 ? ? 1 ? ? 1 ? ? 1 ? ? 2 ? ? 2 ? ? 2 ? ? ?3 ? ? ? 
2 ? ? 2 ? ? 2 ? ? 3 ? ? 3 ? ? 4 ? ? 3 ? ? 3 ? ? 4 ? ? ?4 ? 
3 ? ? 4 ? ? 5 ? ? 4 ? ? 5 ? ? 5 ? ? 4 ? ? 5 ? ? 5 ? ? ?5 ? ? 

Note: I am not considering rearrangements of the same three rows
 to be unique. In other words, the combinations 123, 132, 213, 231, 312,
 321 are all the same as far as I am concerned. If it is not possible to
 do it that way, it will still be helpful, but not quite as helpful. 
Thanks for the help!

... or combn() in utils.

which was the first hit when I googled on "finding combinations in R."

So moral: Use search engines before you post.

Cheers,
Bert

Bert Gunter
Genentech Nonclinical Biostatistics
(650) 467-7374

"Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom."
H. Gilbert Welch




On Tue, Jan 21, 2014 at 12:57 PM, arun <smartpink111 at yahoo.com>
wrote:
> Hi,
> May be this helps:
> library(gtools)
>
> as.data.frame(t(combinations(5,3,1:5)))
> #  V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
> #1  1  1  1  1  1  1  2  2  2   3
> #2  2  2  2  3  3  4  3  3  4   4
> #3  3  4  5  4  5  5  4  5  5   5
> A.K.
>
>
>
> For a column of data, I need to extract all possible unique
> combinations of 3 rows and combine the results into a data frame (as
> columns). So, for example, if I had a column called "test" that
had five rows (the contents of which were the numbers 1:5) all possible
> combinations of 3 rows would be
> 1,2,3
> 1,2,4
> 1,2,5
> 1,3,4
> 1,3,5
> 1,4,5
> 2,3,4
> 2,4,5
> 2,4,5
> 3,4,5
>
> So for this example, R would extract all the combinations shown, and I
would get a data frame that looked like this
> 1     1     1     1     1     1     2     2     2      3
> 2     2     2     3     3     4     3     3     4      4
> 3     4     5     4     5     5     4     5     5      5
>
> Note: I am not considering rearrangements of the same three rows
>  to be unique. In other words, the combinations 123, 132, 213, 231, 312,
>  321 are all the same as far as I am concerned. If it is not possible to
>  do it that way, it will still be helpful, but not quite as helpful.
> Thanks for the help!
>
> ______________________________________________
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> https://stat.ethz.ch/mailman/listinfo/r-help
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http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.