On Oct 6, 2010, at 6:08 PM, Carrie Li wrote:
Thanks a lot!!
Any integer is single element,
Not the way I would have expressed it. An integer is a 4 byte number
(range 2^31 + sign) and a double has a 8 byte floating point
representation (probably specified by some IEEE designation that I
cannot find in the three manual i just searched.) . Numeric vectors
can have any number of elements up to the range of the integer mode
and can be either of mode "integer" or "double". The same maximum
vector length exists for 32 bit and 64 bit versions of R
whereas any number with decimal point is double element ? Is that
right ?
The second part is true, but many double numbers will still be
displayed without decimal points so that is not a good test.
below is what I tried
so, basically, simply force it to be integer would save some space ?
It would be at considerable loss of accuracy if the underlying data is
not well represented as integers.
--
David
P=10000
a=rnorm(P*P)*1000
a=as.integer(a)
D1=matrix(a, nrow=P)
object.size(D1)
>4000112 bytes
b=rnorm(P*P)*1000
D2=matrix(b, nrow=P)
object.size(D2)
>8000112 bytes
On Wed, Oct 6, 2010 at 5:44 AM, David Winsemius <dwinsem...@comcast.net
> wrote:
On Oct 5, 2010, at 11:17 PM, Carrie Li wrote:
Thank you, Henrik! That makes more sense now.
You mentioned that every double value needs 8 bytes. So, in R, how
many
decimal point, or any number smaller than, say 10^4 are considered
as double
value ? (Sorry I don't have any C or Java language background, and
couldn't
find it for R. )
You can specify an integer mode for a vector by using an "L" after
the digits used in its definition or by using mode = integer in the
call to the vector function. You can test for integer statsus with
is.integer and coerce to integer status with as.integer. IN all
other instances you should assume that the storage mode is double.
The storage mode does not vary by element, and an integer vector can
quickly be coerced to double if you make an assignment of double mode.
> a <- c(1L, 2L, 3L)
> a
[1] 1 2 3
> is.integer(a)
[1] TRUE
> a[3] <- 1.2
> is.integer(a)
[1] FALSE
After coercion to double the vector will now take up the full 8
bytes (plus overhead) per element, but is rather set at the vector
level:
> b <- rep(1L, 100)
> object.size(b)
440 bytes
> b[100] <- 1.2 # change single element to double.
> object.size(b)
840 bytes
--
David.
I appreciate your explanation and helps!
On Tue, Oct 5, 2010 at 8:32 PM, Henrik Bengtsson
<h...@stat.berkeley.edu>wrote:
On Tue, Oct 5, 2010 at 5:21 PM, Carrie Li <carrieands...@gmail.com>
wrote:
I am sorry that it has been couple days.
I've read the website you provided below, but still don't quite know
if
this
is doable.
The maximum vector length is 2^31-1, so here is what I tired, and it
returned errors as below.
P=20000
D=matrix(rep(0, P*P), nrow=P)
Error: cannot allocate vector of size 1.5 Gb
In addition: Warning messages:
1: In as.vector(data) :
Reached total allocation of 1535Mb: see help(memory.size)
On the manuals, it says "32-bit OSes by default limit file sizes to
2GB
",
so why P=20000 is not working here ?
Every double value (e.g. 0) needs 8 bytes. So the total memory needed
for that matrix is 8*P*P = 3.2e+09 bytes = 3.2e+09/1024^3 Gb = 2.98Gb.
Now, in order to do anything useful you also need space for creating
an internal copy or two of that object. That is, you basically need
2-3 times more *free* (and *contiguous/non-fragmented*) RAM than that
to do anything useful.
/Henrik
Thanks for any helps. I appreciate.
On Sat, Oct 2, 2010 at 12:22 PM, Marc Schwartz <marc_schwa...@me.com>
wrote:
On Oct 2, 2010, at 11:14 AM, Carrie Li wrote:
Hi everyone,
If I run on a 64-bit R, what is the maximum matrix size that it can
handle ?
Is a matrix 20,000 x 20,000 possible on 32 bit ?
Thanks for answering!
A matrix is a vector with 'dim' attributes. The maximum vector
length is
2^31 - 1 and that does not change between 32 and 64 bit R. The primary
advantage of 64 bit R is the larger memory address space.
See:
http://cran.r-project.org/doc/manuals/R-admin.html#Choosing-between-32_002d-and-64_002dbit-builds
HTH,
Marc Schwartz
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PLEASE do read the posting guide
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and provide commented, minimal, self-contained, reproducible code.
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______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
