[R] Conditional expand.grid()

[Hesen Peng]

Ahhhhh, that's exactly what I'm looking for. Thanks a lot.

On Sat, Jul 11, 2009 at 11:23 AM, jim holtman<jholtman at gmail.com> wrote:
> ?combn
>
>> combn(10,2)
>     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12]
> [,13] [,14] [,15] [,16] [,17]
> [1,]    1    1    1    1    1    1    1    1    1     2     2     2
>  2     2     2     2     2
> [2,]    2    3    4    5    6    7    8    9   10     3     4     5
>  6     7     8     9    10
>     [,18] [,19] [,20] [,21] [,22] [,23] [,24] [,25] [,26] [,27] [,28]
> [,29] [,30] [,31] [,32] [,33]
> [1,]     3     3     3     3     3     3     3     4     4     4     4
>    4     4     5     5     5
> [2,]     4     5     6     7     8     9    10     5     6     7     8
>    9    10     6     7     8
>     [,34] [,35] [,36] [,37] [,38] [,39] [,40] [,41] [,42] [,43] [,44] [,45]
> [1,]     5     5     6     6     6     6     7     7     7     8     8     9
> [2,]     9    10     7     8     9    10     8     9    10     9    10    10
>
>
> On Sat, Jul 11, 2009 at 9:23 AM, Hesen Peng<hesen.peng at emory.edu> wrote:
>> Hello my R buddies,
>>
>> I'm trying to generate a bivariate data.frame with the elements of
>> first row greater than the second row. The more complicated method
>> that I can think of is:
>>
>>   n <- 10
>>   temp <- expand.grid(1:n,1:n)
>>   temp<-temp[temp[,1]>temp[,2],]
>>
>> However, I guess there must be some easier way of doing this. Besides,
>> if inequality condition is applied at the very beginning, this will
>> save me a lot of memory if n goes to a very large number. Is there any
>> suggestions? Thanks a lot.
>>
>> Best wishes,
>>
>> --
>> 彭河森 Hesen Peng
>> http://hesen.peng.googlepages.com/
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem that you are trying to solve?
>



-- 
彭河森 Hesen Peng
http://hesen.peng.googlepages.com/