[R] r help message

Prof Brian D Ripley ripley at stats.ox.ac.uk
Thu Jan 18 08:13:31 CET 2001

On Thu, 18 Jan 2001, S.McClatchie wrote:

> Colleagues
> ----------------------------------
> System info:
> R version rw1020 on NT
> ESS using emacs ver. 20.4
> ----------------------------------
> To keep my scripts short and tidy, I want to call sub-functions and return
> variables from these for subsequent use in the calling function.
> e.g.
> "test.smooth.opc.time.series" <-
>   function()
> {
>   load.opc.ascii.files()
> }
> Within the sub-function "load.opc.ascii.files" I have tried two ways of
> assigning variables for use by the calling function
> "test.smooth.opc.time.series":
>  dir <<- c('h:/data/nov99_tan9913/opc/')
> This works but clutters the workspace.
> assign(dir,  c('h:/data/nov99_tan9913/opc/')), envir =
> test.smooth.opc.time.series)
> Which returns an odd error telling me there is an invalid first argument
> in assign. I don't see why, after reading the help on this function.

The first argument should be a character vector naming the object.
The help page says:

       x: a variable name (given as a quoted string).

and dir is not a quoted string, is it?  What's odd?

You don't need the c() in either case.

Also, test.smooth.opc.time.series is not an environment: you need
parent.frame(), I think.

Is this really a good idea?  The normal idea is to collect return variables
into a list and return that.  Explicit use of assign or <<- in S/R
user code is normally a sign of design problems, although they are needed
in system code.

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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