Re: [R] data.frame() size

From: Matthew Dowle <mdowle_at_concordiafunds.com>
Date: Fri 09 Dec 2005 - 20:43:39 EST

That explains it. Thanks. I don't need rownames though, as I'll only ever use integer subscripts. Is there anyway to drop them, or even better not create them in the first place? The memory saved (90%) by not having them and 10 times speed up would be very useful. I think I need a data.frame rather than a matrix because I have columns of different types in real life.

> rownames(d) = NULL

Error in "dimnames<-.data.frame"(`*tmp*`, value = list(NULL, c("a", "b" :

        invalid 'dimnames' given for data frame

-----Original Message-----
From: pd@pubhealth.ku.dk [mailto:pd@pubhealth.ku.dk] On Behalf Of Peter Dalgaard
Sent: 08 December 2005 18:57
To: Matthew Dowle
Cc: 'r-help@stat.math.ethz.ch'
Subject: Re: [R] data.frame() size

Matthew Dowle <mdowle@concordiafunds.com> writes:

> Hi,
>
> In the example below why is d 10 times bigger than m, according to
> object.size ? It also takes around 10 times as long to create, which
> fits with object.size() being truthful. gcinfo(TRUE) also indicates a
> great deal more garbage collector activity caused by data.frame() than
> matrix().
>
> $ R --vanilla
> ....
> > nr = 1000000
> > system.time(m<<-matrix(integer(1), nrow=nr, ncol=2))
> [1] 0.22 0.01 0.23 0.00 0.00
> > system.time(d<<-data.frame(a=integer(nr), b=integer(nr)))
> [1] 2.81 0.20 3.01 0.00 0.00 # 10 times longer
>
> > dim(m)
> [1] 1000000 2
> > dim(d)
> [1] 1000000 2 # same dimensions
>
> > storage.mode(m)
> [1] "integer"
> > sapply(d, storage.mode)
> a b
> "integer" "integer" # same storage.mode
>
> > object.size(m)/1024^2
> [1] 7.629616
> > object.size(d)/1024^2
> [1] 76.29482 # but 10 times bigger
>
> > sum(sapply(d, object.size))/1024^2
> [1] 7.629501 # or is it ? If its not
> really 10 times bigger, why 10 times longer above ?

Row names!!

> r <- as.character(1:1e6)
> object.size(r)
[1] 72000056
> object.size(r)/1024^2
[1] 68.6646

'nuff said?

-- 
   O__  ---- Peter Dalgaard             ุster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)                  FAX: (+45) 35327907

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Received on Fri Dec 09 20:42:13 2005

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