How to calculate sum of property in tree?

How to calculate sum of property in tree?

[Rainer Hansen]

Hi,

I would like Emacs to calculate the price for the travel cost
(21.90). This should be calculated as sum of the values of the property
"Price" in the elements of the tree. How do I do that in Emacs Lisp?

----------------------------------------------
* Travel cost -- 21.90 EUR

** Train Eusirchen -- Bonn, src_emacs-lisp{(org-entry-get (point) "Price")} EUR 
   :PROPERTIES:
   :Price:    7.70
   :END:
** Bus Euskirchen -- Stotzheim, src_emacs-lisp{(org-entry-get (point) "Price")} EUR
   :PROPERTIES:
   :Price:    2.40
   :END:

** Taxi Bonn, src_emacs-lisp{(org-entry-get (point) "Price")} EUR
   :PROPERTIES:
   :Price:    11.80
   :END:
----------------------------------------------

Thanks!

Rainer

Re: How to calculate sum of property in tree?

[Rainer Hansen]

> Hi,
>
> I would like Emacs to calculate the price for the travel cost
> (21.90). This should be calculated as sum of the values of the property
> "Price" in the elements of the tree. How do I do that in Emacs Lisp?

I found one way to do it. I defined the COLUMNS property with %Price{+},
i.e. sum numbers in column 'Price and format result with `%.2f'
(always two decimals after point). After that I added the property
'Price' and, while cursor on 'Price',  with `C-c C-c (`org-property-action')' and choosing option c
(compute) the value of 'Price' got calculated.

I added the same inline Emacs Lisp expression to the headline to include
the result (21.90) in the headline.

-------8<----------------8<-------------
* Travel cost -- src_emacs-lisp{(org-entry-get (point) "Price")} EUR
  :PROPERTIES:
  :COLUMNS:  %Price{+;%.2f}
  :Price:    21.90
  :END:

** Train Eusirchen -- Bonn, src_emacs-lisp{(org-entry-get (point) "Price")} EUR 
   :PROPERTIES:
   :Price:    7.70
   :END:
** Bus Euskirchen -- Stotzheim, src_emacs-lisp{(org-entry-get (point) "Price")} EUR
   :PROPERTIES:
   :Price:    2.40
   :END:

** Taxi Bonn, src_emacs-lisp{(org-entry-get (point) "Price")} EUR
   :PROPERTIES:
   :Price:    11.80
   :END:
-------8<----------------8<-------------

Any ideas on how to improve that solution?


Rainer Hansen <rainer.hansen@gmx.net> writes:

>
> ----------------------------------------------
> * Travel cost -- 21.90 EUR
>
> ** Train Eusirchen -- Bonn, src_emacs-lisp{(org-entry-get (point) "Price")} EUR 
>    :PROPERTIES:
>    :Price:    7.70
>    :END:
> ** Bus Euskirchen -- Stotzheim, src_emacs-lisp{(org-entry-get (point) "Price")} EUR
>    :PROPERTIES:
>    :Price:    2.40
>    :END:
>
> ** Taxi Bonn, src_emacs-lisp{(org-entry-get (point) "Price")} EUR
>    :PROPERTIES:
>    :Price:    11.80
>    :END:
> ----------------------------------------------
>
> Thanks!
>
> Rainer