On Aug 1, 2012, at 16:34 , Sarah Goslee wrote:
> combn() gives ordered combinations, while expand.grid() gives all
> combinations.
...and there's one more function that is designed to tabulate a function of two
variables over a grid. And yet another one to find which value is max in an
array and return the array indices.
> I'd give worked code but this hints at homework to me.
>
Yes... And since I would expect that most can solve the stated problem in their
head, I wonder what the question is, and how it involves R.
> Sarah
>
> On Wed, Aug 1, 2012 at 10:23 AM, Eik Vettorazzi <e.vettora...@uke.de> wrote:
>> Hi,
>> not sure if that is what you are looking for, but have a look at
>>
>> cmb<-t(combn(c(0,3,5,8),2)) #get all pairs of combinations
>> cbind(cmb,apply(cmb,1,diff)) #for each pair, get the difference
>>
>> cheers
>>
>>
>> Am 01.08.2012 12:29, schrieb loyolite270:
>>> Hi
>>>
>>> I need to optimize the below function:
>>>
>>> a=function(x){
>>> A=x[1]
>>> B=x[2]
>>> C=B-A
>>> return(C)
>>> }
>>>
>>> I need to optimize the above function such that x can be any combination of
>>> these number (0,3,5,8) of vector length 2
>>> (i.e) x can be (3,0), (5,0), (8,0), (3,5), (3,8), (5,8), ...... etc
>>>
>>> can someone please help me solve this problem ?
>>>
>>>
>>>
>
>
> --
> Sarah Goslee
> http://www.functionaldiversity.org
>
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--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
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Email: pd....@cbs.dk Priv: pda...@gmail.com
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