NROW and NCOL on NULL

Rui Barradas · 2023-09-23T21:38:29Z

?s 20:41 de 23/09/2023, Simone Giannerini escreveu: > I know it's documented and I know there are other ways to guard > against this behaviour, once you know about this. > The point is whether it might be worth it to make NCOL and NROW return > the same value on NULL and make R more consistent/intuitive and > possibly less error prone. > > Regards, > > Simone > > On Sat, Sep 23, 2023 at 7:50?PM Duncan Murdoch wrote: >> >> It's been documented for a long time that

Rui Barradas

Sat, Sep 23, 2023 2:38 PM

?s 20:41 de 23/09/2023, Simone Giannerini escreveu:

Hello,

The way I think of this behavior that made it intuitive is to think that 
in R matrices are column-major, therefore if length(NULL) == 0 then NULL 
can be seen as a matrix with one column and zero rows, no data.

Here are other examples for which that reasoning works:


m <- matrix(integer(0L))
NCOL(m)
NROW(m)

x <- integer(0L)
NCOL(x)
NROW(x)


Not very convincing? Maybe with time...

Hope this helps,

Rui Barradas

Thread (8 messages)

Simone Giannerini NROW and NCOL on NULL Sep 23 Duncan Murdoch NROW and NCOL on NULL Sep 23 Simone Giannerini NROW and NCOL on NULL Sep 23 Ben Bolker NROW and NCOL on NULL Sep 23 Rui Barradas NROW and NCOL on NULL Sep 23 Duncan Murdoch NROW and NCOL on NULL Sep 23 Simone Giannerini NROW and NCOL on NULL Sep 24 Martin Maechler NROW and NCOL on NULL Sep 25