[R] Data.frames can not hold objects...What can be done in the following scenario?

[Onur Uncu]

Thank you Duncan. A follow-up question is, how can I achieve the
desired result in the earlier email? (i.e. Add the resulting vectors
as a new column to the existing data.frame?)   I tried the following:

testframe$newcolumn<-apply(testframe,1,function(x)testfun(x[1],x[2]))

but I am getting the following error:

Error in `$<-.data.frame`(`*tmp*`, "vecss", value = c(2, 3, 4, 3, 4, 5
: replacement has 3 rows, data has 2

Thanks for the help.


On Sun, Jun 10, 2012 at 12:02 PM, Duncan Murdoch
<murdoch.duncan at gmail.com> wrote:
> On 12-06-10 6:41 AM, Onur Uncu wrote:
>>
>> R-Help community,
>>
>> I understand that data.frames can hold elements of type double, string
>> etc but NOT objects (such as a matrix etc).
>
>
> That is incorrect.  Dataframes can hold list vectors.  For example:
>
> A <- data.frame(x = 1:3)
> A$y <- list(matrix(1, 2,2), matrix(2, 3,3), matrix(3,4,4))
>
> A[1,2] will now extract the 2x2 matrix, A[2,2] will extract the 3x3, etc.
>
> Duncan Murdoch
>
> This is not convenient for
>>
>> me in the following situation. I have a function that takes 2 inputs
>> and returns a vector:
>>
>> testfun<- function (x,y) seq(x,y,1)
>>
>> I have a data.frame defined as follows:
>>
>> testframe<-data.frame(xvalues=c(2,3),yvalues=c(4,5))
>>
>> I would like to apply testfun to every row of testframe and then
>> create a new column in the data.frame which holds the returned vectors
>> as objects. Why do I want this? Because the returned vectors are an
>> intermediate step towards further calculations. It would be great to
>> keep adding new columns to the data.frame with the intermediate
>> objects. But this is not possible since data.frames can not hold
>> objects as elements. What do you suggest as an elegant solution in
>> this scenario? Thank you for any help!
>>
>>
>>
>>
>>
>>
>>
>>
>> I would love to hear if forum
>>
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>
>