Re: [O] Computations on properties

[Eric Abrahamsen]

Thorsten Jolitz <address@hidden> writes:

> Eric Abrahamsen <address@hidden> writes:
>
>> Thierry Pellé <address@hidden> writes:
>>
>>> Hi,
>>>   I'm seeking how to do something like that
>>>
>>> Let the following text inserted in an org-mode file
>>>
>>> * Mean Calculation
>>>  :PROPERTIES:
>>>  :VAL1: 5
>>>  :VAL2: 10
>>>  :COEF: 10
>>>  :END:
>>>
>>> I would like to append the result of a computation 
>>> like RES=(VAL1*COEF+VAL2)/(COEF+1) 
>>>
>>> Something like 
>>> * Mean Calculation
>>> ...
>>>   :END:
>>>
>>> Mean Calculation=RES (where RES is the value of the result)
>>>
>>> I think to do this with a python script but is there a more org-mode/emacs
>>> method to do it?
>>
>> Sometimes I think it would be nice to have a way to draw property values
>> directly into a babel block, the way you can with table data. Sort of
>> like:
>>
>> * Heading
>>   :PROPERTIES:
>>   :ID:       3f78f08a-ccca-4fc0-aba9-2a192f7a0e5a
>>   :foo:  5
>>   :bar:  puppy
>>   :END:
>>
>> #+BEGIN_SRC emacs-lisp :var alist=3f78f08a-ccca-4fc0-aba9-2a192f7a0e5a
>>
>> And in the block, the "alist" variable would look like '(:foo 5 :bar
>> "puppy").
>>
>> What would be even better would be to run a tags search on matching
>> headlines and feed all property drawers into a single block, as a list
>> of alists. Just thinking out loud...
>
> This is probably not really what you want, but at least somehow related. I
> would not know how to do this via source-block arguments, but maybe you can
> use the results of one source-block (that produces the data) as input for
> another source-block that does the real work. 

Sure, it's certainly doable, and in more than one way, but I think
that's part of the problem: the reason the table-to-src-block-var
process is so great is that it feels purpose-built to do what it does.
For properties you've got search, column view, and the API, but it never
quite feels like the potential is unlocked...

> * Heading 1 :match:
>   :PROPERTIES:
>   :ID:       3f78f08a-ccca-4fc0-aba9-2a192f7a0e5a
>   :foo:  5
>   :bar:  puppy
>   :END:
>
> * Heading 2
>   :PROPERTIES:
>   :ID:       3f78f08a-ccca-4fc0-aba9-2a192f7a0e5b
>   :foo:  6
>   :bar: yuppy
>   :END:
>
>
> * Heading 3 :match:
>   :PROPERTIES:
>   :ID:       3f78f08a-ccca-4fc0-aba9-2a192f7a0e5c
>   :foo:  7
>   :bar:  hippie
>   :END:
>
>
> #+begin_src emacs-lisp :results raw
>    (let ((lst))
>       (org-map-entries
>        (lambda () (cons (org-entry-properties) lst))
>        "match" 'file))
> #+end_src
>
> #+results:
> ((((FILE . /home/tj/News/drafts/drafts/419) (TAGS . :match:) (ALLTAGS
> . :match:) (BLOCKED . ) (ID . 3f78f08a-ccca-4fc0-aba9-2a192f7a0e5a) (foo . 5)
> (bar . puppy) (CATEGORY . 419))) (((FILE . /home/tj/News/drafts/drafts/419)
> (TAGS . :match:) (ALLTAGS . :match:) (BLOCKED . ) (ID .
> 3f78f08a-ccca-4fc0-aba9-2a192f7a0e5c) (foo . 7) (bar . hippie) (CATEGORY .
> 419))))