Ok, good idea. Will add that in to ?data.table ... Thanks
> On 6/7/2012 12:46 PM, Juliet Hannah wrote: >> Hi Yike, >> >> In Matthew's email, he writes: >> >> So in other words, when i has no key it's the first column of i to the >> first column of x's key, the 2nd column of i to the 2nd column of x's >> key, >> etc. > Right, I figured that was the part which was supposed to answer the > question, however the language is ambiguous in Matt's reply, which is > why I asked for clarification. If what you're saying is the case, then > what the docs should say is something along the lines of... > > "If i is not keyed, then data.table performs a join on a positional > match between the columns of i and the keys of X. In other words, a join > is performed on (column 1 of i, column 1 of key of X, then column 2 of > i, column 2 of key of X, etc...)" > > Don't have to use my wording, but the original was ambiguous to me. > > Cheers, > Yike >> >> >> I think this answers my original question. In the example (which is >> from the FAQ), i has no key. So it seems >> the *default* is to match the first column of i to x's key. >> >> That's how data.table "knows". It uses the first column as default. >> >> At least that's the way I understand things now. Matthew, please >> correct if I've misunderstood. >> >> Regards, >> >> Juliet >> i-bin/mailman/listinfo/datatable-help > _______________________________________________ datatable-help mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
