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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] 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 <[EMAIL PROTECTED]> 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 Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
______________________________________________
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
