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