[R] Objects within environment

[Megh Dal]

Thanks Duncan, I understood. Your explanation is really great. Thank you so much for your time.

--- On Wed, 7/21/10, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:

> From: Duncan Murdoch <murdoch.duncan at gmail.com>
> Subject: Re: [R] Objects within environment
> To: "Megh Dal" <megh700004 at yahoo.com>
> Cc: r-help at stat.math.ethz.ch
> Date: Wednesday, July 21, 2010, 10:15 PM
> On 21/07/2010 12:27 PM, Megh Dal
> wrote:
> > Hi Duncan, thanks for your clarification. However I do
> not think I could really understand the "envir" argument in
> objects() function.....
> > 
> > It is saying "an alternative argument for
> name........" Is the "alternative" means the alternative of,
> let say, "package:graphics" (which is the name of an
> environment?). Can you give me an example of an alternative
> argument of that particular environment?
> >   
> 
> as.environment("package:graphics") is an environment. 
> "package:graphics" is its name.
> > This is "specifying the environment evaluation
> environment." What does the phase "environment evaluation
> environment" mean? Can you give me an example?
> >   
> 
> That looks like a typo to me.  "Environment evaluation
> environment" is meaningless.
> > "Mostly there for back compatibility": again totally
> in dark, what does it mean for "back compatibility?" An
> example would definitely be great.
> >   
> 
> Presumably some older release of R used envir, and we still
> have it so that old code will still work.  But that's a
> signal that new code should never need to use it.
> > Toy said "you need to give an environment, not the
> name of one". If I call someone I need to call with his
> name, right? Then if I need to give an environment then,
> without its name how can I do so?
> >   
> 
> This is a computer language, not a conversation. 
> Words have technical meanings that aren't always perfect
> matches to English meanings of the same words.  Here
> the "name" of an environment is what you get when you ask
> for the "name" attribute of it.  There are lots of
> different ways to refer to objects other than by the "name"
> in that technical sense.  For example, you could say
> 
> x <- as.environment("package:graphics") # uses the
> environment's "name"
> ls(envir=x) # refers to it by a variable holding it.
> 
> Duncan Murdoch
> > Can you please explain me in simple english? I think R
> help file should use more non-technical simple english
> language so that student like me can understand R in more
> easier way!
> > 
> > --- On Wed, 7/21/10, Duncan Murdoch <murdoch.duncan at gmail.com>
> wrote:
> > 
> > > From: Duncan Murdoch <murdoch.duncan at gmail.com>
> > > Subject: Re: [R] Objects within environment
> > > To: "Megh Dal" <megh700004 at yahoo.com>
> > > Cc: r-help at stat.math.ethz.ch
> > > Date: Wednesday, July 21, 2010, 4:48 PM
> > > On 21/07/2010 5:57 AM, Megh Dal
> > > wrote:
> > > > Hi all, I have following environments loaded
> with my
> > > current R session:
> > > > > >> search()
> > > > [1] ".GlobalEnv"   
>    > "package:stats" >   
> "package:graphics" > "package:grDevices"
> > > > [5] "package:utils" >   
> "package:datasets" >
> "package:methods"   "Autoloads"   > 
>    [9] "package:base"    > >
> How can I find the objects under a specific
> > > environment? Here I tries following:
> > > > > >> objects(envir="package:base")
> > > > Error in objects(envir = "package:base") :
> invalid
> > > 'envir' argument
> > > > > > It would be great if somebody
> would point me the
> > > correct arguments for object() function to find
> the onjects
> > > associated with it. In help file it is written
> that:
> > > > " envir: an alternative argument to
> ‘name’ for
> > > specifying the
> > > >       > 
>   environment evaluation environment. Mostly
> > > there for back
> > > >       > 
>   compatibility"
> > > > What is the wrong in my code?
> > > > The easiest way to pick an item from the
> search list is by
> > > number:
> > > > objects(3)
> > >  or
> > > ls(3)
> > > > will give you the objects in the graphics
> package, with the
> > > search list as above.  You can also specify
> the name as
> > > the name argument, e.g.
> > > > objects("package:base")
> > > > If you want to use the envir argument
> (why?), you need to
> > > give an environment, not the name of one.
> > > > Duncan Murdoch
> > > > 
> > 
> >         
> 
>