[R] blockwise sums

[Lutz Prechelt]

I am looking for a function like 
  my.blockwisesum(vector, n)
that computes sums of disjoint subsequences of length n from vector
and can work with vector lengths that are not a multiple of n.

It should give me for instance
  my.blockwisesum(1:10, 3) == c(6, 15, 24, 10)

Is there a builtin function that can do this?
One could do it by coercing the vector into a matrix of width n,
and then use apply,
but that is cumbersome if the length is not divisible by n, 
is it not?
Any other ideas?

  Lutz

Prof. Dr. Lutz Prechelt;  prechelt at inf.fu-berlin.de
Institut fuer Informatik; Freie Universitaet Berlin
Takustr. 9; 14195 Berlin; Germany
+49 30 838 75115; http://www.inf.fu-berlin.de/inst/ag-se/