On Mon, Jun 8, 2009 at 3:04 PM, baptiste auguie
<baptiste.auguie@gmail.com>wrote:

> Marie Sivertsen wrote:
>
>> Dear list,
>>
>> I have a vector of elements which I want to combined each with each, but
>> none with itself. For example,
>>
>>
>>
>>> v <- c("a", "b", "c")
>>>
>>>
>>
>> and I need a function 'combine' such that
>>
>>
>>
>>> combine(v)
>>>
>>>
>> [[1]]
>> [1] "a" "b"
>>
>> [[2]]
>> [1] "a" "b"
>>
>> [[3]]
>> [1] "b" "c"
>>
>> I am not very interested in the orders of the output items for now, and
>> the
>> form can be something differs from list, like matrix or data frame. I know
>> of 'expand.grid', but it will combine each item with each item including
>> itself, so not what I wants.
>>
>> Could you help me please.  Thank you.
>>
>> Mvh.,
>> Marie
>>
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>>
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>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
> I guess you actually want,
>
> [[1]]
> [1] "a" "b"
>
> [[2]]
> [1] "a" "c" # not "a" "b" again



Yes I made a mistake.  Thank you.

Mvh.,
Marie



>
>
> [[3]]
> [1] "b" "c"
>
>
> if so, try
>
> ?combn
> > combn(v,2)
>    [,1] [,2] [,3]
> [1,] "a"  "a"  "b"
> [2,] "b"  "c"  "c"
>
>
> HTH,
>
> baptiste
>
> --
> _____________________________
>
> Baptiste Auguié
>
> School of Physics
> University of Exeter
> Stocker Road,
> Exeter, Devon,
> EX4 4QL, UK
>
> Phone: +44 1392 264187
>
> http://newton.ex.ac.uk/research/emag
> ______________________________
>
>

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