cbind/rbind inconsistency with NULL parameter (PR#3585)
That's as documented, on the help page. (NULL is a zero-length argument.) There's even a reason given. Exactly which part of the help page did you not understand?
On Tue, 29 Jul 2003 jmartin2003@notamusica.com wrote:
R-Version: 1.7.1 (2003-06-16) OS: Debian/GNU Linux cbind and rbind handle NULL parameters inconsistently. Consider:
> cbind()
NULL
> cbind(NULL)
NULL And:
> cbind(diag(x = 1, 1, 1))
[,1] [1,] 1
> cbind(NULL, diag(x = 1, 1, 1))
[,1] [1,] 1 These seem to indicate that NULL parameters will be ignored in any call to cbind and rbind. However:
cbind(NULL, diag(x = 1, 0, 1))
[,1] [,2] I.e. if one dimension of another parameter to cbind/rbind is zero, cbind/rbind will create a row/column from the NULL parameter. This inconsistency creates problems in the construction of matrices within loops and similar constructs.
So? It's a documented feature.
Brian D. Ripley, ripley@stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595