Another tool I find useful is Matthew Dowle's data.table package. It has very fast indexing, can have much lower memory requirements than a data frame, and has some built-in data manipulation capability. Especially with a 64-bit OS, you can use this to keep things in memory where you otherwise would have to use a database.
See here: http://article.gmane.org/gmane.comp.lang.r.packages/282 - Tom ______________________________________________ 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.