[R] Choice of data.frame column by index?

[Rolf Turner]

On 24/08/2007, at 12:51 PM, Moshe Olshansky wrote:

> This won't work since it produces a matrix (try this).

	On the contrary, Patrick's solution is correct.  I tried it.  It  
works just fine.

			cheers,

				Rolf Turner

> What should work is
> x[(1:nrow(x)) + nrow(x)*(v-1)]
>
> --- Johannes Graumann <johannes_graumann at web.de>
> wrote:
>
>> Thanks!
>>
>> Joh
>>
>> On Thursday 23 August 2007 12:01:50 you wrote:
>>> x[cbind(1:nrow(x), the.vector)]
>>>
>>> Patrick Burns
>>> patrick at burns-stat.com
>>> +44 (0)20 8525 0696
>>> http://www.burns-stat.com
>>> (home of S Poetry and "A Guide for the Unwilling S
>> User")
>>>
>>> Johannes Graumann wrote:
>>>> Hello,
>>>>
>>>> Imagine a data frame like so:
>>>>
>>>>  Intensity0 Intensity1
>>>> 1   767432.1   451743.4
>>>> 2  3998988.0  4642145.0
>>>> 3   818974.6   552315.8
>>>>
>>>> and a vector like so:
>>>>
>>>> [1] 1 2 1
>>>>
>>>> How can I get R to produce a vector that contains
>> the value in one column
>>>> or the other depending on the vector? The result
>> should look like
>>>>
>>>> [1] 767432.1 4642145.0 818974.6
>>>>
>>>> Thanks for any hints!
>>>>
>>>> Joh
>>>>
>>>> ______________________________________________
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>>>> 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.
>>
>>
>>> ______________________________________________
>> R-help at stat.math.ethz.ch 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.
>>
>
> ______________________________________________
> R-help at stat.math.ethz.ch 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.


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