save an object by dynamicly created name

On Nov 1, 2009, at 11:28 PM, Henrik Bengtsson wrote:

On Sun, Nov 1, 2009 at 7:48 PM, David Winsemius <dwinsemius at comcast.net>
wrote:

On Nov 1, 2009, at 10:16 PM, Henrik Bengtsson wrote:

path <- "data";
dir.create(path);

for (i in 1:10) {
?m <- i:5;
?filename <- sprintf("m%02d.Rbin", i);
?pathname <- file.path(path, filename);
?save(m, file=pathname);
}

That would result in each of the ten files containing an object with the
same ?name == "m". (Also on my system R data files have type Rdta.) So I
thought what was requested might have been a slight mod:

path <- "~/";
dir.create(path);

for (i in 1:10) {
?assign( paste("m", i, sep=""), ?i:5)
?filename <- sprintf("m%02d.Rdta", i)
?pathname <- file.path(path, filename)
?obj =get(paste("m", i, sep=""))
?save(obj, file=pathname)
}

Then a more convenient solution is to use saveObject() and
loadObject() of R.utils. ?saveObject() does not save the name of the
object save.

The OP asked for this outcome :

" I would like to save m as m1, m2, m3 ...,
to file /home/data/m1, /home/data/m2, home/data/m3, ..."

?If you want to save multiple objects, the wrap them up
in a list.

I agree that a list would makes sense if it were to be stored in one file ,
although it was not what requested.

But wouldn't that require assign()-ing a name before list()-wrapping?

str(a)

str(b)

str(c)

I suppose we ought to mention that the use of assign to create a variable is
a FAQ ... 7.21? Yep, I have now referred to it a sufficient number of times
to refer to it by number.

http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-can-I-turn-a-string-into-a-variable_003f

--
David

?loadObject() does not assign variable, but instead return
them. Example:

library("R.utils");
x <- list(a=1,b=LETTERS,c=Sys.time());
saveObject(x, file="foo.Rbin");
y <- loadObject("foo.Rbin");
stopifnot(identical(x,y));

So, for the original example, I'd recommend:

library("R.utils");
path <- "data";
mkdirs(path);

for (i in 1:10) {
?m <- i:5;
?filename <- sprintf("m%02d.Rbin", i);
?saveObject(m, file=filename, path=path);
}

and loading the objects back as:

for (i in 1:10) {
?filename <- sprintf("m%02d.Rbin", i);
?m <- loadObject(filename, path=path);
?print(m);
}
/Henrik

--
David.

/H

On Sun, Nov 1, 2009 at 6:53 PM, jeffc <hcen at andrew.cmu.edu> wrote:

Hi,

I would like to save a few dynamically created objects to disk. The
following is the basic flow of the code segment

for(i = 1:10) {
?m = i:5
?save(m, file = ...) ## ???
}
To distinguish different objects to be saved, I would like to save m as
m1,
m2, m3 ..., to file /home/data/m1, /home/data/m2, home/data/m3, ...

I tried a couple of methods on translating between object names and
strings
(below) but couldn't get it to work.
https://stat.ethz.ch/pipermail/r-help/2008-November/178965.html
http://tolstoy.newcastle.edu.au/R/help/04/08/2673.html

Any suggestions would be appreciated.

thanks

Hao

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David Winsemius, MD
Heritage Laboratories
West Hartford, CT

David Winsemius, MD
Heritage Laboratories
West Hartford, CT