Às 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 <murdoch.dun...@gmail.com> wrote:
It's been documented for a long time that NCOL(NULL) is 1. What
particular problems did you have in mind? There might be other ways to
guard against them.
Duncan Murdoch
On 23/09/2023 1:43 p.m., Simone Giannerini wrote:
Dear list,
I do not know what would be the 'correct' answer to the following but
I think that they should return the same value to avoid potential
problems and hard to debug errors.
Regards,
Simone
---------------------------------------
NCOL(NULL)
[1] 1
NROW(NULL)
[1] 0
sessionInfo()
R version 4.3.1 RC (2023-06-08 r84523 ucrt)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 11 x64 (build 22621)
Matrix products: default
locale:
[1] LC_COLLATE=Italian_Italy.utf8 LC_CTYPE=Italian_Italy.utf8
[3] LC_MONETARY=Italian_Italy.utf8 LC_NUMERIC=C
[5] LC_TIME=Italian_Italy.utf8
time zone: Europe/Rome
tzcode source: internal
attached base packages:
[1] stats graphics grDevices utils datasets methods base
loaded via a namespace (and not attached):
[1] compiler_4.3.1
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
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