Hi all,
I'm not sure if this is a feature or a bug (and I did read the FAQ and the posting guide, but am still not sure). Some of my students have been complaining and I thought I just might ask: Let K be a vector of length k. If one types dim(K), you get NULL rather than [1] k. Is this logical?
Here's the way I explain it (and maybe someone can provide a more accurate explanation of what's going on): R has several types of scalar (atomic) values, the most common of which are numeric, integer, logical, and character values. Arrays are data structures which hold only one type of atomic value. Arrays can be one-dimensional (vectors), two-dimensional (matrices), or n-dimensional.
(We generally use arrays of n-1 dimensions to populate n-dimensional arrays -- thus, we generally use vectors to populate matrices, and matrices to populate 3-dimensional arrays, but could use any array of dimension < n-1 to populate an n-dimensional array.)
It logically follows that when one does dim() on a vector, one should *not* get NULL, but should get the length of the vector (which one *could* obtain by doing length(), but I think this is less logical). I think that R should save length() for lists that have objects of different dimension and type.
Does this make sense? Or is there a better explanation?
Thanks in advance! Yours,
Olivia Lau
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