[R] Value Lookup from File without Slurping

[Gabor Grothendieck]

If "that" refers to using a database on disk to temporarily hold
the file then example 6 on the home page shows it, as mentioned,
and you may wish to look at the other examples there too and
there is further documentation in the ?sqldf help file.

On Fri, Jan 16, 2009 at 11:11 AM, Gundala Viswanath <gundalav at gmail.com> wrote:
> Hi,
>
>> Unless you specify an in-memory database the database is stored on disk.
>
> Thanks for your explanation.
> I just downloaded 'sqldf'.
>
> Where can I find the option for that? In sqldf I can't see the command.
>
> I looked at:
> envir = parent.frame()
>
> doesn't appear to be the one.
>
> - Gundala Viswanath
> Jakarta - Indonesia
>
>>
>> On Fri, Jan 16, 2009 at 10:59 AM, Gundala Viswanath <gundalav at gmail.com> wrote:
>>> Hi Gabor,
>>>
>>>> the file itself is read  into a database
>>>
>>> The above doesn't use RAM memory?
>>>
>>> Rgds,
>>> GV.
>>>
>>>> without ever going through R so your memory requirements correspond to what
>>>> you extract, not the size of the file.
>>>>
>>>> On Fri, Jan 16, 2009 at 10:49 AM, Gundala Viswanath <gundalav at gmail.com> wrote:
>>>>> 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")
>>>>>>
>>>>>> ______________________________________________
>>>>>> R-help at 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.
>>>>>>
>>>>>
>>>>
>>>
>>
>