[R] Problem with as.data.frame when an extra attribute is present

[Frank E Harrell Jr]

Prof Brian Ripley wrote:
> It's quite intentional, as it is the documented behaviour of data.frame:
> 
>      Objects passed to 'data.frame' should have the same number of
>      rows, but atomic vectors, factors and character vectors protected
>      by 'I' will be recycled a whole number of times if necessary.
> 
>> data.frame(a = structure(1, label="foo"), b = c(2, 3))
> Error in data.frame(a = structure(1, label = "foo"), b = c(2, 3)) :
>         arguments imply differing number of rows: 1, 2
> 
> It is safe to replicate a vector without any attributes, but not safe to 
> replicate this 'a': you will have to do it yourself if you know it is 
> safe.  How is anyone to know you meant 'label' to apply to the whole 
> vector and not the single element of the vector (if you did)?

Thanks Brian for clarifying that.  Is there a way to use a specially 
written as.data.frame.labelled function to do this?  I assume there is 
no way to use I() here.

Frank

> 
> 
> On Thu, 9 Nov 2006, Frank E Harrell Jr wrote:
> 
>> I have a problem when one of the vectors in a list needs to be
>> replicated to have the appropriate length, and an attribute is present.
>>
>> > w <- list(a=1, b=2:3)
>> > as.data.frame(w)
>>   a b
>> 1 1 2
>> 2 1 3
>>
>> > attr(w$a,'label') <- 'foo'
>> > as.data.frame(w)
>> Error in data.frame(a = 1, b = c(2, 3), check.names = TRUE) :
>>         arguments imply differing number of rows: 1, 2
>>
>> I usually use the Hmisc label function to make a variable of class
>> 'labelled' and define as.data.frame.labelled as as.data.frame.vector,
>> but that also fails here.  Any help appreciated.  -Frank
>>
>> > sessionInfo()
>> R version 2.2.1, 2005-12-20, i486-pc-linux-gnu [also fails in 2.4.0]
>>
>> attached base packages:
>> [1] "methods"   "stats"     "graphics"  "grDevices" "utils"     
>> "datasets"
>> [7] "base"
>>
>>
> 


-- 
Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University