vectors of different length in a matrix

HI!

I?ve 3 vectors of different length (a,b,c) and want to arrange them in a 
matrix a,b,c as rows and the figures of these vectors in the columns 
(with that matrix i want to calculate a distance between thes vectors - 
vegan - vegdist - horn). Is there a possibilty to create such a matrix 
and to fill up the missing fields with NA?s automatically????

Filling with NA's is the hard part; R normally likes to recycle vectors 
that are too short.

Here's one way, probably not the best:

x <- matrix(NA, 3, max(length(a), length(b), length(c)))
x[1,seq(along=a)] <- a
x[2,seq(along=b)] <- b
x[3,seq(along=c)] <- c

Another way to do it would be to extend all the vectors to the same 
length by appending NAs, then using rbind.

Duncan Murdoch