[R] ls() pattern question

[Bert Gunter]

Actually fun( param != something..) is syntactically incorrect in the first
place for any function!

ls sees "pat != whatever"  as the "name" argument of ls() and can't make
any sense of it, of course.

Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Wed, Jul 14, 2021 at 5:01 PM Andrew Simmons <akwsimmo using gmail.com> wrote:

> Hello,
>
>
> First, `ls` does not support `!=` for pattern, but it's actually throwing a
> different error. For `rm`, the objects provided into `...` are substituted
> (not evaluated), so you should really do something like
>
> rm(list = ls(pattern = ...))
>
> As for all except "con", "DB2", and "ora", I would try something like
>
> setdiff(ls(), c("con", "DB2", "ora"))
>
> and then add `rm` to that like
>
> rm(list = setdiff(ls(), c("con", "DB2", "ora")))
>
> On Wed, Jul 14, 2021 at 7:41 PM Kai Yang via R-help <r-help using r-project.org>
> wrote:
>
> > Hello List,
> > I have many data frames in environment.  I need to keep 3 data frames
> > only, con DB2 and ora.
> > I write the script to do this.
> > rm(ls(pattern != c("(con|DB2|ora)")))
> >
> >
> > but it give me an error message:
> >
> >
> > Error in rm(ls(pattern != c("(con|DB2|ora)"))) :
> >   ... must contain names or character strings
> >
> > I think the pattern option doesn't support != ? and is it possible to fix
> > this?
> > Thank you,
> > Kai
> >
> >
> >
> >         [[alternative HTML version deleted]]
> >
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>
>         [[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.
>

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