[R] sapply and loop

Roger D. Peng
Sat, 16 Oct 2004 12:14:52 -0000

You can use system.time() to time your procedure.  There's no guarantee that
sapply() will be faster than a for() loop, especially if you preallocate the
matrices.

-roger

Zhen Pang wrote:

> Dear all,
>
> I am doing 200 times simulation. For each time, I generate a matrix and
> define some function on this matrix to get a 6 dimension vector as my
> results.
>
> As the loop should be slow, I generate 200 matrice first, and save them
> into a list named ma,
> then I define zz<-sapply(ma, myfunction)
>
> To my surprise, It almost costs me the same time to get my results if I
> directly use a loop from 1 to 200. Is it common? Can I improve any further?
>
> Ps, how to count the exact time to finish my code?
>
> Thanks.
>
> Zhen
>
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--
Roger D. Peng