Re: Org-babel `:hlines yes` no longer working for python

From: "Eric Schulte" <schulte.eric@gmail.com>
To: Christopher Allan Webber <cwebber@dustycloud.org>
Cc: emacs-orgmode@gnu.org
Subject: Re: Org-babel `:hlines yes` no longer working for python
Date: Sat, 26 Jun 2010 13:45:35 -0700	[thread overview]
Message-ID: <87k4pla5g0.fsf@gmail.com> (raw)
In-Reply-To: <87d3vd1rkc.fsf@dustycloud.org> (Christopher Allan Webber's message of "Sat, 26 Jun 2010 15:12:35 -0500")

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Hi Christopher,

I'm certainly no Python expert, but I implemented your idea of
converting "hlines" to and from "None"'s (patch below [1]), and it seems
to work (under some definition of work).  See the following example with
the new behavior.

--8<---------------cut here---------------start------------->8---
#+tblname: many-cols
| a | b | c |
|---+---+---|
| d | e | f |
|---+---+---|
| g | h | i |

#+source: echo-table
#+begin_src python :var tab=many-cols :hlines yes
  return tab
#+end_src

#+results: echo-table
| a | b | c |
|---+---+---|
| d | e | f |
|---+---+---|
| g | h | i |
--8<---------------cut here---------------end--------------->8---

Please, Python people, try this out and if you like the behavior then
I'll happily apply the patch.

Best -- Eric

Christopher Allan Webber <cwebber@dustycloud.org> writes:

> Hey Eric,
>
> Thanks for the super helpful reply!
>
> Out of curiosity, is it likely that we will ever get hline support in
> Python and etc?  I've been pondering how it might be done, and maybe it
> could be like this, using a '|-' string instead of a list for the row:
>
> [['a', 'b', 'c'], '|-', ['d', 'e', 'f'], ['g', 'h', 'i']]
>
> Which would produce:
>
> | a | b | c |
> |---+---+---|
> | d | e | f |
> | g | h | i |
>
> Alternately maybe the same thing could be done by abusing None:
>
> [['a', 'b', 'c'], None, ['d', 'e', 'f'], ['g', 'h', 'i']]
>
> Thoughts?
>  - cwebb
>
> "Eric Schulte" <schulte.eric@gmail.com> writes:
>
>> Hi Christopher,
>>
>> Thanks for pointing this out, this is an error in the documentation,
>> which I will update.  The code you posted should generate the error you
>> have received.
>>
>> Currently the only language which can handle hlines is emacs-lisp, all
>> other languages will result in errors like the one you pasted below.
>> That's not to say that it wouldn't be possible to add hline handling to
>> other languages, or to maybe do something tricky like session-based
>> evaluation in which an `hlines' variable was pre-initialized to some
>> value, but I digress.
>>
>> Note that it *is* possible to have hlines in the output, using colnames,
>> e.g.
>>
>>
>> --8<---------------cut here---------------start------------->8---
>> #+tblname: A
>> | a | b | c |
>> |---+---+---|
>> | d | e | f |
>> | g | h | i |
>>
>> #+begin_src python :var tab=A :colnames yes
>> return [[val + '*' for val in row] for row in tab]
>> #+end_src
>>
>> #+results:
>> | a  | b  | c  |
>> |----+----+----|
>> | d* | e* | f* |
>> | g* | h* | i* |
>> --8<---------------cut here---------------end--------------->8---
>>
>> which works because the hline, and the column names, are never made
>> available to python, rather Babel holds onto them and then re-applies
>> them to the source block's output.
>>
>> or even to have an elisp block add hlines to your results
>>
>>
>> --8<---------------cut here---------------start------------->8---
>> #+tblname: many-cols
>> | a | b | c |
>> |---+---+---|
>> | d | e | f |
>> |---+---+---|
>> | g | h | i |
>>
>> #+source: echo-table
>> #+begin_src python :var tab=many-cols
>>   return tab
>> #+end_src
>>
>> #+begin_src emacs-lisp :var table=echo-table
>>   (butlast (apply #'append (mapcar (lambda (el) (list el 'hline)) table)))
>> #+end_src
>>
>> #+results:
>> | a | b | c |
>> |---+---+---|
>> | d | e | f |
>> |---+---+---|
>> | g | h | i |
>> --8<---------------cut here---------------end--------------->8---
>>
>> Thanks for pointing this out!
>>
>> Best -- Eric
>>
>> Christopher Allan Webber <cwebber@dustycloud.org> writes:
>>
>>> Hello all,
>>>
>>> I was going through the tutorial and testing the :hlines yes feature as
>>> described in the info manual.  Unfortunately, the example given no
>>> longer seems to work for python:
>>>
>>> #+tblname: many-cols
>>> | a | b | c |
>>> |---+---+---|
>>> | d | e | f |
>>> |---+---+---|
>>> | g | h | i |
>>>
>>> #+source: echo-table
>>> #+begin_src python :var tab=many-cols :hlines yes
>>>   return tab
>>> #+end_src
>>>
>>> #+results: echo-table
>>> | a | b | c |
>>> | d | e | f |
>>> | g | h | i |
>>>
>>> In the buffer *Org-Babel Error Output* I see:
>>>
>>> Traceback (most recent call last):
>>>   File "<stdin>", line 6, in <module>
>>>   File "<stdin>", line 3, in main
>>> NameError: global name 'hline' is not defined
>>>
>>> In emacs-lisp this still seems to work though.  But I also see that in
>>> emacs lisp hlines are represented by the hline symbol.  I'm guessing
>>> that the python equivalent was trying to do the same thing, but no hline
>>> variable exists in python?
>>>
>>> Thanks!
>>>  - cwebb
>>>
>>> _______________________________________________
>>> Emacs-orgmode mailing list
>>> Please use `Reply All' to send replies to the list.
>>> Emacs-orgmode@gnu.org
>>> http://lists.gnu.org/mailman/listinfo/emacs-orgmode

Footnotes: 
[1]  

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diff --git a/lisp/babel/langs/ob-python.el b/lisp/babel/langs/ob-python.el
index 2ce9e1d..29bb166 100644
--- a/lisp/babel/langs/ob-python.el
+++ b/lisp/babel/langs/ob-python.el
@@ -96,7 +96,7 @@ called by `org-babel-execute-src-block'."
 specifying a var of the same value."
   (if (listp var)
       (concat "[" (mapconcat #'org-babel-python-var-to-python var ", ") "]")
-    (format "%S" var)))
+    (if (equal var 'hline) "None" (format "%S" var))))
 
 (defun org-babel-python-table-or-string (results)
   "If the results look like a list or tuple, then convert them into an
@@ -110,7 +110,9 @@ Emacs-lisp table, otherwise return the results as a string."
                  "\\[" "(" (replace-regexp-in-string
                             "\\]" ")" (replace-regexp-in-string
                                        ", " " " (replace-regexp-in-string
-                                                 "'" "\"" results))))))
+                                                 "'" "\""
+						 (replace-regexp-in-string
+						  "None" "hline" results t)))))))
      results)))
 
 (defvar org-babel-python-buffers '(:default . nil))

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