Hi Sebastien,

On Dec 8, 2009, at 11:37 AM, Sébastien Vauban wrote:

> Hi Thomas,
>
> "Thomas S. Dye" wrote:
>> On Dec 7, 2009, at 11:50 PM, Sébastien Vauban wrote:
>>
>>>> [2] I guess one could potentially think about dealing with  
>>>> missing values
>>>>    more explicitly in org-babel. E.g. there could be a header arg
>>>>    specifying what values are to be treatyed as missing. Nothing  
>>>> like
>>>>    that exists currently.
>>>
>>> I guess such a feature would be required on the long term. Of  
>>> course, even
>>> specifying what would be the needed behavior is already difficult,  
>>> I think.
>>> One must have good knowledge of the multiple languages and  
>>> environments,
>>> and try to abstract the best behavior out of these.
>>>
>>> Side note -- I know, for example, that there is an option in  
>>> Access to let
>>> it consider the empty string ('') as the NULL value, or not. Clear.
>>>
>>> But what's a "NA" value in general?  Is 0 always a meaningful  
>>> value as
>>> numeric?  Context-sensitive..
>>
>> NA is a logical constant of length 1 which contains a missing value
>> indicator. Whether or not 0 is a meaningful value as numeric  
>> depends on your
>> data and the questions you are asking of it. You don't ask this  
>> question,
>
> ?  I thought I addressed that when asking (to myself) "Is 0 always a
> meaningful value as numeric?" and answering [that it certainly is]
> "context-sensitive.."
>
>
>> but if I read this thread correctly and you are trying to  
>> workaround a data
>> input problem with R in Org-babel,
>
> No, you misread, or I mis-wrote ;-)
>
> I wasn't speaking of R only, saying that "such a feature would be  
> required on
> the long term [... for] the multiple languages".
>
> Thinking at shell-script (with empty strings), SQL code (with empty  
> strings
> and NULL values), etc.
>
>
>> then replacing missing values with 0 in a numeric context to get  
>> around the
>> Org-babel problem is NOT a good idea.
>
> Implementing a fixed interpretation is NOT a good idea. I share your  
> point of
> view.
>
> My comments were:
>
> - I think we must be able to write a rule for interpreting  
> "empty" (whatever
>  it means) values;
>
> - We should think at what's needed to cover the current and future  
> needs, not
>  focusing on one specific language (R), but thinking at all of them  
> (shell
>  commands, SQL, etc.).
>
> Best regards,
>  Seb
>
> -- 
> Sébastien Vauban

I agree with you on the importance of having some way to represent  
missing values in Org-babel that can be translated cleanly and  
transparently to the representations used by specific languages.

I was responding to one part of your longer message in the context of  
the message subject, "R questions."  I see now that you were asking a  
more general question.  Mea culpa.

All the best,
Tom

Thomas S. Dye, Ph.D.
T. S. Dye & Colleagues, Archaeologists, Inc.
Phone: (808) 529-0866 Fax: (808) 529-0884
http://www.tsdye.com