[R] Value Lookup from File without Slurping

Gundala Viswanath gundalav at gmail.com
Fri Jan 16 16:49:52 CET 2009


Hi Gabor,

Do you mean storing data in "sqldf', doesn't take memory?
For example, I have 3GB data file. with standard R object using read.table()
the object size will explode twice ~6GB. My current 4GB RAM
cannot handle that.

Do you mean with "sqldf", this is not the issue?
Why is that?

Sorry for my naive question.

- Gundala Viswanath
Jakarta - Indonesia



On Fri, Jan 16, 2009 at 9:09 PM, Gabor Grothendieck
<ggrothendieck at gmail.com> wrote:
> On Fri, Jan 16, 2009 at 5:52 AM, r at quantide.com <r at quantide.com> wrote:
>> I agree on the database solution.
>> Database are the rigth tool to solve this kind of problem.
>> Only consider the start up cost of setting up the database. This could be a
>> very time consuming task if someone is not familiar with database
>> technology.
>
> Using sqldf as mentioned previously on this thread allows one to use
> the SQLite database with no setup at all.  sqldf automatically creates
> the database, generates the record layout, loads the file (not going through
> R but outside of R so R does not slow it down) and extracts the
> portion you want into R issuing the appropriate calls to RSQLite/DBI and
> destroying the database afterwards all automatically.  When you
> install sqldf it automatically installs RSQLite and the SQLite database
> itself so the entire installation is just one line: install.packages("sqldf")
>
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