Re: [R] memory cleaning

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Fri 22 Jul 2005 - 23:52:13 EST

See help("gc") and read up about garbage collection. Memory measurements without a preceding gc() are meaningless.

You have not told us your version of R, but 2.1.0 and later do use much less memory in write.table. Nevertheless, they do have to convert each column to character and that does take some memory.

On Fri, 22 Jul 2005, Claude Messiaen - Urc Necker wrote:

> Hi R Users,
> After some research I haven't find what I want.
> I'm manipulating a dataframe with 70k rows and 30 variables, and I run out of memory when exporting this in a *.txt file
>
> after some computing I have used :
>
>> memory.size()/1048576.0
> [1] 103.7730
>
> and I make my export :
>
>> write.table(cox,"d:/tablefinal2.txt",row.names=F,sep=';')
>> memory.size()/1048576.0
> [1] 241.9730
>
> I'm surprised so I try removing some objects :
>> rm (trait,tany,tnor,toth,suivauxdany,dnor,doth,mod1,
> mod2,mod3,lok1,lok2,lok3,aux,risque,risk)
> and check memory space :
>> memory.size()/1048576.0
> [1] 242.1095
>
> First, I don't understand why when removing objects the memory used increase ?
> Next, why the memory used double when I make an export ?
> I look forward to your reply
>
> Claude
>
> [[alternative HTML version deleted]]
>
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-- 
Brian D. Ripley,                  ripley@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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Received on Fri Jul 22 23:57:37 2005

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