[R] Dealing With Extremely Large Files
ggrothendieck at gmail.com
Sat Sep 27 02:56:46 CEST 2008
Not sure if it applies to your file or not but if it does then the
sqldf package facilitates reading a large file into an SQLite database.
Its a front end to RSQLite which is a front end to SQLite and it
reads the data straight into the database without going through
R so R does not limit it in any way -- its only actuated from R.
The code to do this is basically just two lines of code. You don;t
have to install database software (its included with RSQLite package)
and you don't have to set up a database at all -- it does that for you
See example 6e on the home page which creates a database
transparently, reads in the data and extracts random rows from
the database into R:
On Fri, Sep 26, 2008 at 3:55 PM, zerfetzen <zerfetzen at yahoo.com> wrote:
> I'm sure that a large fixed width file, such as 300 million rows and 1,000
> columns, is too large for R to handle on a PC, but are there ways to deal
> with it?
> For example, is there a way to combine some sampling method with read.fwf so
> that you can read in a sample of 100,000 records, for example?
> Something like this may make analysis possible.
> Once analyzed, is there a way to, say, read in only x rows at a time, save
> and score each subset separately, and finally append them back together?
> I haven't seen any information on this, if it is possible. Thank you for
> reading, and sorry if the information was easily available and I simply
> didn't find it.
> View this message in context: http://www.nabble.com/Dealing-With-Extremely-Large-Files-tp19695311p19695311.html
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