[R] Extract information from S4 object

[Martin Morgan]

On 02/22/2010 08:46 AM, Jay wrote:
> Tahnk you. But, when I try the command you both suggested I get a NULL
> as the results.
> 
>> names(object1 @ x.values)
> NULL
> 
> Where did I go wrong?
> 
> 
> On Feb 22, 4:34 pm, David Winsemius <dwinsem... at comcast.net> wrote:
>> On Feb 22, 2010, at 8:05 AM, Jay wrote:
>>
>>
>>
>>> The function prediction() returns this:
>>
>>> Formal class 'performance' [package "ROCR"] with 6 slots
>>>  ..@ x.name      : chr "Cutoff"
>>>  ..@ y.name      : chr "Accuracy"
>>>  ..@ alpha.name  : chr "none"
>>>  ..@ x.values    :List of 1
>>>  .. ..$ : Named num [1:89933] Inf 2.23 2.22 2.17 2.16 ...
>>>  .. .. ..- attr(*, "names")= chr [1:89933] "" "36477" "56800"

predobj at x.values is a list. The first element of the list
predobj at x.values[[1]] is a numeric vector. The numeric vector has names.
So names(predobj at x.values[[1]]).

Martin

>>> "41667" ...
>>>  ..@ y.values    :List of 1
>>>  .. ..$ : num [1:89933] 0.5 0.5 0.5 0.5 0.5 ...
>>>  ..@ alpha.values: list()
>>
>>> Now, since I want to match each prediction with its original case, I
>>> need to extract the names, i.e. the information in "- attr(*,
>>> "names")= chr [1:89933] "" "36477" "56800" "41667" ..." so I can use
>>> it with a simple datafile[names,] query.
>>
>>> How do I get these names in plain number formats?
>>
>> Not sure what you mean by "plain number formats" but this should get  
>> you a vector of "names" assuming the prediction object is named  
>> "predobject":
>>
>> names( predobj... at x.values )
>>
>> If you wanted them "as.numeric", then that is the name of the  
>> appropriate function.
>>
>> --
>> David
>>
>>
>>
>>> ______________________________________________
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>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>
>> ______________________________________________
>> R-h... at r-project.org mailing listhttps://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
> 
> ______________________________________________
> 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.


-- 
Martin Morgan
Computational Biology / Fred Hutchinson Cancer Research Center
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