Gabor - thanks for your suggestion... I had checked the previous post, but I found (as a new user of R) this approach to be too complicated and I had problems gaining the correct output values. If there is a simpler way of doing this, then please feel free to let me know.
Dylan - thanks, your approach is a good start. In answer to your questions, my data are 43200 columns and 16800 rows as a data frame - I will probably have to read the dataset in segments though, as it won't fit into the memory! I've been able to follow your example - how would I be able to apply this technique for finding the average of each 60 x 60 block? Any other suggestions are of course welcome! Many thanks again, Steve ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.