[R] Querying RData Files, SQL style?

[Bhushan, Vipul]

Thank you for your response. To clarify, I don't mind if R loads the data (in the background), but was hoping to have to only specify the query as a simple request and the list of input files. I'd like to do this relatively efficiently, so searching across ~100 RData files (10 to 100 KB each) only takes many seconds and not lots of minutes or hours. 

-----Original Message-----
From: David Winsemius [mailto:dwinsemius at comcast.net] 
Sent: Friday, July 15, 2011 11:42 AM
To: Bhushan, Vipul
Cc: r-help at r-project.org
Subject: Re: [R] Querying RData Files, SQL style?


On Jul 15, 2011, at 10:29 AM, Bhushan, Vipul wrote:

> Hello. Is there a package or functionality available somewhere which  
> will allow for complex searches (such as what SQL can do) of  
> collections of RData files? Search capability within a given RData  
> file at a time (which could be put in a loop) would be good, but the  
> capability to perform joins to data across multiple RData files  
> would be great. These queries might be ad-hoc, so writing an R  
> program to get(load(...)) each file and customize the search in home- 
> grown R code isn't feasible.

As I read the question it appears that your are not expecting to load  
the data into R and are rather asking for a program other than R (or  
Rscript or littler)  to read .Rdata files and perform database joins.  
As I understand it, that is not available. As I understand it, there  
is not even a package that can look at .Rdata files for their object  
names and structure without actual loading them.

Hoping to be corrected on either of these points.

>
> This shouldn't be dependent on environment details, but just in  
> case: I'm running version 2.13.0 in a Unix environment (but could  
> easily run in Windows too).
>
> Thanks very much.

-- 

David Winsemius, MD
West Hartford, CT