about aggregate

["Shin, David" <David_Shin@ctb.com>]

Hi,

I am a new user of this list. If I say something wrong, please correct and
pardon me. Thanks.

I have a question about "aggregate".
I have a data matrix that is   5000 (rows) x 100(columns).
I want s-plus to compute the means for every 50 rows so that I can get a new
matrix that is 100 x100.

I try this command: aggregate( my.data, ndeltat = 50, fun = mean) , but it
doesn't work.
If someone knows how to do this, would you please tell me.
Thank you very much.

David