[R] more efficient sum of matrix columns

[Jonathan Baron]

On 06/14/03 20:51, Jean Eid wrote:
>Dear R users,
>I am looking for a more efficient way to compute the sum of columns of a
>matrix.
>I am currently using apply(data, 2, sum) however, I am building a data set
>from another one by summing the columns of some parts of the matrix.
>the loop is taking too long (about 1/2 hour) for a 4462 * 202 matrix.

colSums() might be faster, but I don't know how much faster.  It
does not allow na.rm=T, but you don't have that, so it might
help.

--
Jonathan Baron, Professor of Psychology, University of Pennsylvania
R page:               http://finzi.psych.upenn.edu/