Re: [babel] Uses for :session buffers

["Thomas S. Dye" <tsd@tsdye.com>]

On Nov 4, 2009, at 10:44 AM, Stephan Schmitt wrote:

>
> Thomas S. Dye wrote:
>> Aloha all,
>> I'm trying to comprehend the possibilities created by org-babel,  
>> and would like to draw on the experience of others if I could.
>> I recently discovered the buffer created by :session.  In my case,  
>> this is an R session that I am building to track the data  
>> collection phase of a research project.  I was delighted to find  
>> that it appears to have recorded everything my org file had done in  
>> that session.  I have a vague idea that it might be useful to save  
>> this as a log to prove that all the little source blocks in my org  
>> file indeed were called and executed successfully. I'm wondering:  
>> do other org-babelers use the :session buffer?  How?  For what  
>> purpose?
>
> Another advantage: you can set a variable in one source block
> and access it in the next one.
>
> Greetings,
> 	Stephan
>
Aloha Stephan,

Yes, this is a tremendous advantage.

I'm using my org file as a laboratory notebook.  The R source code  
blocks track data entry progress (among other things), so I need to re- 
establish sessions whenever I come back to the project.  I have an R  
source block that I run each time I open the org file.  It looks like  
something like this:

#+src_name r-adze-session
#+begin_src R :session adze :noweb :results output
  library(ggplot2)
  library(xtable)
  <<r-connect>>
  <<r-complete-2>>
  objects()
#+end_src

where <<r-connect>> connects R to our database server and <<r- 
complete-2>> is a query of the database that populates a data frame in  
the R session.  The call to objects() lets me know wether or not the  
session is populated with the objects I'm expecting to be there.

I'm particularly interested in the emacs buffer that is established  
for the session (in this case "adze"), which looks like this when I  
run r-adze-session:

tdye> library(ggplot2)
tdye> library(xtable)
tdye> library(RMySQL)
...

I'm wondering if there is a standard (or intended) use for this file,  
perhaps as a log, or if other org-babelers typically discard it, as  
I've been doing?

All the best,
Tom

>

>> Any tips or advice will be appreciated.
>> All the best,
>> Tom
>> Thomas S. Dye, Ph.D.