Message-ID: <C07600F3B08324418B460FD82E3ADC340C605DAA@exukmb12.eur.nsroot.net>
Date: 2007-12-03T18:41:06Z
From: Rees, David
Subject: Putting a NULL in a list (as cannot pass NA to C++)
Hi,
If I do the following I can have a NULL in a list
> x <- list( 1, list(3,NULL,4), 5 )
> x
[[1]]
[1] 1
[[2]]
[[2]][[1]]
[1] 3
[[2]][[2]]
NULL
[[2]][[3]]
[1] 4
[[3]]
[1] 5
This is a good thing for me as it can be passed through into C++ where I
can know the value is missing. (Can't seem to detect a NA from C++ for
some reason. There is RF_isNull in the API but no RF_isNA that I can
find!)
Is it possible to put a null in an already created list. e.g. now do
> x[[2]][[2]] <- NULL
> x
[[1]]
[1] 1
[[2]]
[[2]][[1]]
[1] 3
[[2]][[2]]
[1] 4
[[3]]
[1] 5
But x[[2]][[2]] has been deleted.
Many thanks
Regards,
David