Re: [R] Extract function parameters from a R expression
If you specifically want to know which packages were loaded by the script
then using a vanilla version of R (i.e. one where only base packages are
loaded):
vanilla_search <- search()
source("myRprg.R")
setdiff(search(), vanilla_search)
On Wed, Jun 20, 2018 at 4:08 AM, Sigbert Klinke
wrote:
> Hi,
>
> I have read an R program with
>
> expr <- parse("myRprg.R")
>
> How can I extract the parameters of a specifc R command, e.g. "library"?
>
> So, if myprg.R containes the lines
>
> library("xyz")
> library("abc")
>
> then I would like to get "xyz" and "abc" back from expr.
>
> Thanks in advance
>
> Sigbert
>
> --
> https://hu.berlin/sk
>
>
>
> __
> R-help@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.
>
--
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com
__
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Re: [R] Extract function parameters from a R expression
... or if the argument is just quoted text or a numeric value as in your
library() example, don't parse the text and use regex's to search for the
function call and pick out the text of the arguments.
Again, this only works (I think) for the simple sort of case of your
example. Beyond that, you'll have to follow Hadley's prescription.
Cheers,
Bert
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, Jun 20, 2018 at 1:26 AM, Hadley Wickham wrote:
> You need to recursively walk the parse tree/AST. See, e.g.,
> https://adv-r.hadley.nz/expressions.html#ast-funs
>
> Hadley
>
> On Wed, Jun 20, 2018 at 10:08 AM, Sigbert Klinke
> wrote:
> > Hi,
> >
> > I have read an R program with
> >
> > expr <- parse("myRprg.R")
> >
> > How can I extract the parameters of a specifc R command, e.g. "library"?
> >
> > So, if myprg.R containes the lines
> >
> > library("xyz")
> > library("abc")
> >
> > then I would like to get "xyz" and "abc" back from expr.
> >
> > Thanks in advance
> >
> > Sigbert
> >
> > --
> > https://hu.berlin/sk
> >
> >
> >
> > __
> > R-help@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.
> >
>
>
>
> --
> http://hadley.nz
>
> __
> R-help@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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Re: [R] Extract function parameters from a R expression
You need to recursively walk the parse tree/AST. See, e.g.,
https://adv-r.hadley.nz/expressions.html#ast-funs
Hadley
On Wed, Jun 20, 2018 at 10:08 AM, Sigbert Klinke
wrote:
> Hi,
>
> I have read an R program with
>
> expr <- parse("myRprg.R")
>
> How can I extract the parameters of a specifc R command, e.g. "library"?
>
> So, if myprg.R containes the lines
>
> library("xyz")
> library("abc")
>
> then I would like to get "xyz" and "abc" back from expr.
>
> Thanks in advance
>
> Sigbert
>
> --
> https://hu.berlin/sk
>
>
>
> __
> R-help@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.
>
--
http://hadley.nz
__
R-help@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.
[R] Extract function parameters from a R expression
Hi,
I have read an R program with
expr <- parse("myRprg.R")
How can I extract the parameters of a specifc R command, e.g. "library"?
So, if myprg.R containes the lines
library("xyz")
library("abc")
then I would like to get "xyz" and "abc" back from expr.
Thanks in advance
Sigbert
--
https://hu.berlin/sk
__
R-help@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.
