[Rd] value returned by by()

Uwe Ligges ligges at statistik.tu-dortmund.de
Wed Sep 15 10:55:26 CEST 2010



On 14.09.2010 20:50, Seb wrote:
> On Tue, 14 Sep 2010 12:02:04 +0200,
> Uwe Ligges<ligges at statistik.tu-dortmund.de>  wrote:
>
>> It returns a list with athe class attribut set to "by", just use: x<-
>> by(.....)  unclass(x)
>
> Thanks Uwe, however, that still returns an array when using the
> data.frame method for by():
>
> R>  class(unclass(with(warpbreaks, by(warpbreaks[, 1:2], tension, summary))))
> [1] "array"
>
> It seems as if the only way to really ensure a list:
>
> R>  class(lapply(unclass(with(warpbreaks, by(warpbreaks[, 1:2], tension, summary))), function(x) x))
> [1] "list"
>
> but it seems like a waste to call another function just to do this.
>
>

Then you could still do

x <- by(.....)
attributes(x) <- NULL

Uwe



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