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renaming objects

4 messages · Giles.Crane at doh.state.nj.us, Gabor Grothendieck, Paul Hammer +1 more

#
Thank you all for your enlightening replies.

Hadley mentioned first that a mere assignment in R does not double storage.
Hence once solution is:
y <- x
rm(x)

Gabor gave a deeper solution which permits assigning a second name:
makeActive Binding("y",function() x, .GlobalEnv)

The reason for my question was to form a function:
    --read, in chunks, a large file which does not fit in memory
    --abstract one variable, which does fit in memory.
    -- save that variable in .Rdata format under a chosen name.

DIAG1 = getvar("bigfile.txt", startchar, endchar)
save(DIAG1, file = "DIAG1.Rdata")

I am now testing this approach.
Cordially,
Giles

Giles Crane, M.Phil., MPH
Research Scientist & Statistician
Tel 609 292-8012, -5666
Fax 609 292-9288
giles.crane at doh.state.nj.us

__________________


This does not really answer your question but the following
lets you refer to an object by a second name although the object
still has its original name as well.
NULL
[1] 3
[1] 4
On Mon, Mar 3, 2008 at 4:20 PM, <Giles.Crane at doh.state.nj.us> wrote:
http://www.R-project.org/posting-guide.html
>
#
You might be able to just read in that single  column rather than
read the file in chunks by using colClasses arg of read.table
with "NULL" for all columns except the one you want.

The sqldf package is another way -- see example 6 on the home
page.  You specify what you want using SQL:
http://sqldf.googlecode.com

readTableIndex in R.utils has the purpose of only reading a single
column.
http://finzi.psych.upenn.edu/R/library/R.utils/html/readTableIndex.html
On Tue, Mar 4, 2008 at 9:52 AM, <Giles.Crane at doh.state.nj.us> wrote:
#
Bingo!

See ?exists

G.
On Tue, Mar 04, 2008 at 04:38:31PM +0100, Paul Hammer wrote: