Dear R-devel, A colleague was recently surprised by the behavior of the ":" operator (as sequence generator), so I decided to dig a little bit. Here are a couple of things I found.
- ?":" seems a bit imprecise. The Details section says: `The operator : and the seq(from, to) form generate the sequence from, from+1, ..., to.' but `to' is not necessarily included in the output; e.g., > 0.5:3 [1] 0.5 1.5 2.5 Then it says: `The second form generates from, from+by, ..., up to the sequence value less than or equal to to.' That's not necessarily true, either, if `by' is negative: > 0.5:-3 [1] 0.5 -0.5 -1.5 -2.5 - It seems counter-intuitive to allow non-integer values as operand for ":". It also seems a bit odd that 1:2 returns something with storage.mode integer, whereas 0.5:2 gives doubles. Would it make sense to disallow non-integer operands to ":"? I can't think of a situation when non-integer operands for ":" would be good... Best, Andy ______________________________________________ R-devel@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
