Hi Tim, Thanks for your comments. They're all valid and quite common to hear from long time R users. I've recently realised that it might help to say a bit about my background and perhaps some name dropping won't hurt. I started using S-plus in 1999. I sat in the same office as Pat Burns, my mentor. He gave me a copy of S Poetry, and guided me through my first ever s-help post. I'm not claiming data.table design decisions are correct, or not dangerous. My *only* claim is that they have been thought through by a long time R/S user, rightly or wrongly. The very first version of data.table was on CRAN in 2006.
Chris has already got most points spot on. Most of the points I've already answered before on this list, on r-help, the FAQs or Stack Overflow. To draw it all together, perhaps the following would be a quick strategy to tackle all your points, in this order : 1. Open the detail of the 15 reviews on Crantastic. There are nice hints and tips there. http://crantastic.org/packages/data-table 2. Rank StackOverflow data.table tag by most voted questions and scroll through : http://stackoverflow.com/questions/tagged/data.table?sort=votes&pagesize=50 In particular the 2nd one tackles the concern about the design of `j` : http://stackoverflow.com/questions/7768686/r-self-reference and this one highlights j's design being used twice in one query : http://stackoverflow.com/questions/10705290/r-select-a-value-for-based-on-a- highest-value-in-another-column There's a danger in concentrating on the most popular only, so also sort by newest as those might discuss the more recent features which by definition haven't been asked about yet or voted for. 3. On the danger of departing from [.data.frame syntax, see this : http://stackoverflow.com/questions/10527072/using-data-table-package-inside- my-own-package (the question may not seem relevant to that point, but the answer is) 4. Read the first section of vignette("datatable-faq") in order starting at 1.1. It's structured with your concerns in mind. 5. Run example(data.table) and follow the results through at the prompt. Don't actually read ?data.table yet. 6. On the danger of data.table not being copied, that's very deliberate as Chris says. See ?copy and run example(copy) at the prompt. I suspect the two key features of data.table you're missig are := and cedta(), which the above links answer hopefully. I've listed it like that, in that order, so hopefully it is very quick to get through. Matthew _______________________________________________ datatable-help mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
