[R] Computing sums of the columns of an array

Uwe Ligges ligges at statistik.uni-dortmund.de
Fri Aug 5 18:24:09 CEST 2005


Martin C. Martin wrote:

> Hi,
> 
> I have a 5x731 array A, and I want to compute the sums of the columns.  
> Currently I do:
> 
> apply(A, 2, sum)


colSums(A)

Uwe Ligges


> But it turns out, this is slow: 70% of my CPU time is spent here, even 
> though there are many complicated steps in my computation.
> 
> Is there a faster way?
> 
> Thanks,
> Martin
> 
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