kjetil.kjernsmo at astro.uio.no
Tue Jul 18 15:29:06 CEST 2000
On Mon, 17 Jul 2000, Prof Brian D Ripley wrote:
>> Error in 1:numeric(0) : NA/NaN argument
>> In some cases, it has seemed to me that it would have been sooo much more
>> convenient if it returned
>Why is that a sensible answer?
Well, I didn't say sensible, I said convenient.... :-) I don't know if it
is sensible (yet), but the reason it I have found it could be convenient
is if I had a vector x, and I wanted elements 1:n, and n in some special
case happened to be unspecified, x[1:n] would also not be specified.
> 1:x expects a length-one vector x,
>preferably an integer one. And 1:0, for example, is not a length-zero
>vector. If x is not specified, 1:x is also not specified. In particular,
>its length is not specified (and hence not specified as zero) and so
>a vector of NAs will not do.
Indeed. In the above case, I would have to compute n, check if is
unspecified, if it is, return numeric(0), if not return the result. If
1:numeric(0) was, well, integer(0), I wouldn't have to worry about those
>If you really, really wanted this it should be integer(0) for consistency.
>(1:n has storage mode integer.)
Fine with me!
>S does try to do sensible things in boundary cases (in the Unix tradition),
>but only where (almost) everyone can agree on what is sensible.
Yes, and it does a good job!
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