[R] a newbie question about "data"

[envisage]

Prof Brian. thanks, I have check the on-line Errata at
http://www.stats.ox.ac.uk/pub/MASS4/Errata4.2 before,  for the second
printing.
I don't know it depends on the first printing Errata at all.

and sorry again for my anonymous posting. I am not a native English
speaker, and I should learn how to observe these proprieties(at least,
some basic network etiquette). I 'll try to correct this as soon as
possible.

Best Regards,

Ma Yun(We put the Last Name before the First name, Ma means horse or
pointless for it's a last name, Yun means cloudy,)
China,P.R.C.
Shanghai. LongDong RD 2386.


On Nov 8, 2007 3:30 PM, Prof Brian Ripley <ripley at stats.ox.ac.uk> wrote:
> A lot of those changes are of course in the on-line Errata at
> http://www.stats.ox.ac.uk/pub/MASS4/Errata4.1 . E.g.
>
> R Changes
> =========
>
> p.12  As from R 1.7.0 data() is not needed for our datasets, but it
>        is needed for R's own datasets  ability.cov, iris3  and swiss
>        prior to R 2.0.0.
>
>
>
> On Thu, 8 Nov 2007, Bill.Venables at csiro.au wrote:
>
> > The book came out in 2002 and a lot has happened with R in the time since then.  In particular it is now possible for R to have 'lazy loading' of objects.  If the person setting up the package has used this option (as they all now should), when the package is loaded R essentially is made aware that the data (and other) objects are there, so it is visible, but it is only read into memory if it is used.  The little tag that alerts R to the existence of the object and triggers the automatic loading on demand is called a 'promise' and the action itself is called a 'delayed assign'.
> >
> > Previously this all had to be done manually.  data() could be used either to discover what data objects were available in packages, or to load them in to memory.  Many old-style packages still require you to do this.  There are cases where it is justified, I suppose, but they are quite hard to think of...
> >
> > With R you have to keep abreast of developments, and it's all happening pretty fast.
> >
> > Bill Venables.
> >
> > PS Since you are new to R, it is not considered very friendly to send messages to the R groups anonymously.
> >
> >
> > Bill Venables
> > CSIRO Laboratories
> > PO Box 120, Cleveland, 4163
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> > mailto:Bill.Venables at csiro.au <mailto:Bill.Venables at csiro.au>
> > http://www.cmis.csiro.au/bill.venables/ <http://www.cmis.csiro.au/bill.venables/>
> >
> > -----Original Message-----
> > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org <mailto:r-help-bounces at r-project.org> ] On Behalf Of envisage
> > Sent: Thursday, 8 November 2007 1:27 PM
> > To: r-help at r-project.org
> > Subject: [R] a newbie question about "data"
> >
> > hi, I am reading Modern Applied Statistics with S 4th ed¡£
> > page4 have these two lines:
> >> library(MASS)
> >> data(chem) # needed in R only
> > but I find withou the line " data(chem)"
> > I can still access chem, isn't it?
> > is it unnecessary or something i missed here?
> > thanks for the replay in advance.
> >
> >
>
> --
> 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 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
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