ls() pattern question
Yes,. Thanks for the clarification. I tried to indicate this with my comment about it being used as the "name" argument of ls(). What I should have said is that it is syntactically wrong as a way to specify an argument of any function -- "myarg != something" does not specify anything about the argument "myarg" of a function not equalling something -- unless, as you pointed out, it positionally matches to "myarg" and evaluates to something. But that was certainly not the OP's intent, and I thought it was worth pointing out that he appeared to be confused about the syntax of argument specification in general. 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 Thu, Jul 15, 2021 at 2:09 AM Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
On 14/07/2021 8:21 p.m., Bert Gunter wrote:
Actually fun( param != something..) is syntactically incorrect in the
first
place for any function!
You have to be careful with absolute statements:
> f <- function(pattern) cat("It's legal!")
> f(pattern != something..)
It's legal! "pattern != something.." is a legal expression, which would return a logical vector. My function didn't ever evaluate it, so the fact that variables named "pattern" and "something.." didn't exist in the global env didn't make any difference. It's legal syntax, just wrong. Duncan Murdoch
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 at 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 at 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]]
______________________________________________ R-help at 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]]
______________________________________________ R-help at 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]]
______________________________________________ R-help at 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.