Thanks a lot to Gabor for his help with the solution of this problem. The solution using "zoo(aggregate)" is easy to implement & efficient. I have calculated the 15min mean values of a 1min wind speed file containing 2.9 million records x 16 columns (size 179 MB) in just 144 seconds (R-2.1.1 running in a GNU/LINUX machine).
Thanks to Bogdan too for his suggested solution using SQL, I have not tried that one yet. Augusto ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
