[R] Why does R do this?

[PIKAL Petr]

Hi

It is documented behaviour.

"An empty index selects all values: this is most often used to replace all the entries but keep the attributes."

so I presume that changing it could break huge amount of code. The only workaround could be to check "z" before using it for indexing.

e.g.
> if(length(z)==0) z <- length(y) + 1
> y[-z]
[1] 1 2 3
>
Cheers
Petr

> -----Original Message-----
> From: R-help <r-help-bounces using r-project.org> On Behalf Of Nick Wray via R-
> help
> Sent: Tuesday, January 8, 2019 10:29 AM
> To: r-help <r-help using r-project.org>
> Subject: [R] Why does R do this?
>
> y<-c(1,2,3)
> z<-which(y>3)
> z
> y<-y[-z]
> y
>
> In the work I'm doing I often have this situation and have to make sure that I
> condition on z being non-zero as y is now numeric(0) rather than the set
> c(1,2,3).  Why does R do this?  Wouldn't it be more sensible for R to simply
> leave the host set unchanged if there are no elements to take out?
>
> Any thoughts?
>
> Thanks, Nick Wray
> [[alternative HTML version deleted]]
>
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