[R] Problem with data.frames

Simon Fear Simon.Fear at synequanon.com
Mon Aug 4 12:09:19 CEST 2003

Peter is right, but there is a point here: it would be nice if
attach(my.dframe) would do nothing - or at least warn - if my.dframe was
already in the search list. Like library(). Attaching twice is almost
to be an error?
Of course in many circumstances it might be better to use with() than
attach() - if you haven't come across with(), it works like attach()
with an
inbuilt detach() when the parentheses close.

Aside 1: it would also be nice if ?attach pointed to ?with. Is this kind
suggestion best sent to r-help or r-devel?

Aside 2: is with() efficient, or does it create a copy of the dataset? 


-----Original Message-----
From: Peter Dalgaard BSA [mailto:p.dalgaard at biostat.ku.dk]
Sent: 04 August 2003 00:52
To: Andreas Eckner
Cc: r-help at stat.math.ethz.ch
Subject: Re: [R] Problem with data.frames

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Andreas Eckner <andreas.eckner at soundinvest.net> writes:

> Hi,
> I just encountered a problem in R that may easily be fixed: If one
> attach for a data.frame e.g. 10000 times and forgets detach, then R
> incredibly slow (less then 10% of the original speed).

R also gets incredibly slow if you create 10000 copies of your data
set, which is effectively the same thing! The fix is: Don't do that... 

   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907

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Simon Fear
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