[R] any updates w.r.t. lapply, sapply, apply retaining classes

Hadley Wickham hadley at rice.edu
Fri Nov 4 01:36:07 CET 2011

>    I agree that it is non-trivial to solve the cases you & I have posed.
>  However, I would wholeheartedly support having an error spit back for any
> function that does not explicitly support a class.  In this case, if I
> attempt to do   sapply(x, class), and 'x' is of class "difftime", then I
> should receive an error "sapply cannot function upon class 'difftime' ".
>  Why do I take this stance?  There are at least 2 strong reasons:

I don't see why that command should be a problem because class()
returns a string.

A better example might be sapply(x, identity) which in general you
would hope to be identical to x:

x <- structure(1:10, class = "blah")
identical(x, sapply(x, identity))
# [1] FALSE


Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University

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