[R-pkg-devel] vapply and More Complex FUN.VALUE

[Uwe Ligges]

On 27.09.2023 09:35, Ivan Krylov wrote:
> On Tue, 26 Sep 2023 20:00:03 +0000
> Dario Strbenac <dstr7320 using uni.sydney.edu.au> wrote:
> 
>> Is it possible to somehow specify more complex return types, such as
>> a data.frame with specific columns?
> 
> Probably not with vapply(). It only looks at the equivalent of
> typeof(), verifies the length() (which for data.frames is the number of
> columns) and then combines the objects along the axis that you're not
> interested in (building a list-matrix).
> 
> I've been using the do.call(rbind, lapply(...)) idiom, relying on
> rbind.data.frame to check its arguments. It could probably be made more
> efficient, but it does the job.
> 

Or perhaps you simply look for defining a new class (I'd use S3) where 
the output is a specific data frame (with some prefedined columns) to 
which you assign a class attribute?

Best,
Uwe Ligges