[Rd] Severe memory problem using split()

[Martin Morgan]

On 07/12/2010 01:45 PM, cstrato wrote:
> Dear all,
> 
> With great interest I followed the discussion:
> https://stat.ethz.ch/pipermail/r-devel/2010-July/057901.html
> since I have currently a similar problem:
> 
> In a new R session (using xterm) I am importing a simple table
> "Hu6800_ann.txt" which has a size of 754KB only:
> 
>> ann <- read.delim("Hu6800_ann.txt")
>> dim(ann)
> [1] 7129   11
> 
> 
> When I call "object.size(ann)" the estimated memory used to store "ann"
> is already 2MB:
> 
>> object.size(ann)
> 2034784 bytes
> 
> 
> Now I call "split()" and check the estimated memory used which turns out
> to be 3.3GB:
> 
>> u2p  <- split(ann[,"ProbesetID"],ann[,"UNIT_ID"])
>> object.size(u2p)
> 3323768120 bytes

I guess things improve with stringsAsFactors=FALSE in read.delim?

Martin

> 
> During the R session I am running "top" in another xterm and can see
> that the memory usage of R increases to about 550MB RSIZE.
> 
> 
> Now I do:
> 
>> object.size(unlist(u2p))
> 894056 bytes
> 
> It takes about 3 minutes to complete this call and the memory usage of R
> increases to about 1.3GB RSIZE. Furthermore, during evaluation of this
> function the free RAM of my Mac decreases to less than 8MB free PhysMem,
> until it needs to swap memory. When finished, free PhysMem is 734MB but
> the size of R increased to 577MB RSIZE.
> 
> Doing "split(ann[,"ProbesetID"],ann[,"UNIT_ID"],drop=TRUE)" did not
> change the object.size, only processing was faster and it did use less
> memory on my Mac.
> 
> Do you have any idea what the reason for this behavior is?
> Why is the size of list "u2p" so large?
> Do I make any mistake?
> 
> 
> Here is my sessionInfo on a MacBook Pro with 2GB RAM:
> 
>> sessionInfo()
> R version 2.11.1 (2010-05-31)
> x86_64-apple-darwin9.8.0
> 
> locale:
> [1] C
> 
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
> 
> Best regards
> Christian
> _._._._._._._._._._._._._._._._._._
> C.h.r.i.s.t.i.a.n   S.t.r.a.t.o.w.a
> V.i.e.n.n.a           A.u.s.t.r.i.a
> e.m.a.i.l:        cstrato at aon.at
> _._._._._._._._._._._._._._._._._._
> 
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-- 
Martin Morgan
Computational Biology / Fred Hutchinson Cancer Research Center
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