[R] blockwise sums

Lutz Prechelt prechelt at pcpool.mi.fu-berlin.de
Tue Aug 31 14:19:29 CEST 2004

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?


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/

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