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: Sun, 27 Jun 2010 16:43:42 -0700	[thread overview]
Message-ID: <87wrtk6nyp.fsf@gmail.com> (raw)
In-Reply-To: <878w611bi4.fsf@dustycloud.org> (Christopher Allan Webber's message of "Sat, 26 Jun 2010 20:59:31 -0500")

Hi,

OK, I've applied this patch.

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

> Eric,
>
> Looks good to me!  It's abusing the None type's meaning a little, but
> I think it's acceptable enough.  (If you think of hlines as rows that
> are not rows, you can trick yourself into thinking it is perfectly
> pythonic :))
>

Yea, this semantic mismatch bothered me, however it looks like Python
doesn't have anything like symbols that could be used here, and I guess
there isn't an issue of wanting to preserve "None" for "nil" mapping
because "nil" can be represented with an empty list "[]".

Thanks for bringing this up! -- Eric

>
>  - cwebb
>
> "Eric Schulte" <schulte.eric@gmail.com> writes:
>
>> 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]  
>>
>> 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))