[R] Understanding which

[Eric Berger]

Here's a hint:

> y <- which(x>100)
> identical(y,y)
# TRUE
> identical(y,-y)
# TRUE

The '-' is misleading - it is absorbed into the empty y, leaving the
request x[y] to be x for an empty set of indices.

HTH,
Eric



On Wed, Apr 18, 2018 at 2:13 PM, Ashim Kapoor <ashimkapoor using gmail.com> wrote:

> Dear All,
>
> Here is a reprex:
>
> > x<- 1:100
> > x[-which(x>100)]
> integer(0)
>
> In words, I am finding out which indices correspond to values in x which
> are  greater than  100 ( there are no such items ) . Then I remove those
> indices. I should get back the x that I started with since there are no
> items in x which are bigger than 100 . Instead, it is returning an empty
> vector.
>
> Why is this ? What am I misunderstanding?
>
> Best Regards,
> Ashim
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/
> posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

	[[alternative HTML version deleted]]