[R] Re : Large database help
Robert Citek
rwcitek at alum.calberkeley.org
Tue May 16 22:57:46 CEST 2006
On May 16, 2006, at 11:19 AM, Prof Brian Ripley wrote:
> Well, there *is* a manual about R Data Import/Export, and this does
> discuss using R with DBMSs with examples. How about reading it?
Thanks for the pointer:
http://cran.r-project.org/doc/manuals/R-data.html#Relational-
databases
Unfortunately, that manual doesn't really answer my question. My
question is not about how do I make R interact with a database, but
rather how do I make R interact with a database containing large sets.
> The point being made is that you can import just the columns you
> need, and indeed summaries of those columns.
That sounds great in theory. Now I want to reduce it to practice.
In the toy problem from the previous post, how can one compute the
mean of a set of 1e9 numbers? R has some difficulty generating a
billion (1e9) number set let alone taking the mean of that set. To wit:
bigset <- runif(1e9,0,1e9)
runs out of memory on my system. I realize that I can do some fancy
data shuffling and hand-waving to calculate the mean. But I was
wondering if R has a module that already abstracts out that magic,
perhaps using a database.
Any pointers to more detailed reading is greatly appreciated.
Regards,
- Robert
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