I don't understand what you think it should actually return. As for why it
should behave the way it does now... hmmm, keep in mind that each
sub-expression needs to make sense as well.
Consider -integer(0)... applying the unary negation operator to a vector of
integers yields a new vector of the same length as the original one where each
element has had its sign changed. If there are no elements in the vector to
begin with, there should be no elements in the result. With no elements in the
result, there is nowhere to for the negative sign to have an effect. Thus,
-integer(0) is the same as integer(0). R would have to recognize the
-integer(0) expression as a whole and treat it specially to get a different
result than the result it gives now, and I don't like the idea that
length(a[-integer(0)]) might be non-zero as a special case even though
length(integer(0)) is zero. So, no, I definitely don't agree with you.
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On October 11, 2014 2:25:14 AM PDT, PO SU <rhelpmaill...@163.com> wrote:
>
>Dear helpeRs,
> let a <- 1:10
> let b <- integer(0) first, then i will randomly write a integer
>differently in the range(1,10) or NULL into b. for supposed 5 times.
> then i want to get a[-b],that means i not want the values at index
>b.
> if any time of 5 times generate a integer, it works fine. but when
>all the 5 times generate NULL, it can't work!
> Because of the a[-integer(0)] =integer(0) .
> I ask the same question once before, now i encount it again, i think
>a[-integer(0)] should return a not integer(0) !
> Is any one have the same idea with me ? or give me a oppisite case
>that a[-integer(0)] need to be integer(0) ?
>
>
>
>
>
>--
>
>PO SU
>mail: desolato...@163.com
>Majored in Statistics from SJTU
>______________________________________________
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>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.
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