Re: [O] org table calc and lisp for hh:mm timetable

[Martin Halder]

>> If we're not just looking for a neat workaround for some special cases 
>> anymore, but looking at making org-tables aware of time-like strings 
>> by default, a better strategy than to convert them into integers might 
>> be to translate them into Calc time format and back again.
>> 
>> After all, Calc and hence the Org spreadsheet already handles time 
>> arithmetic perfectly well, it's just that it would be nice to have 
>> this functionality with the extra option to enter and display times as 
>> =12:45= rather than =12@ 45'= or =12h 45m=.
>> 
> 
> I did not realize that calc (and hence Org) already supported operating
> on time values.  The =7@ 30'= format does indeed work well for time
> table formulas (although the =12h 5m= format does not), e.g.,
> 
> | 1@ 20' | 2 | 0@ 40' 0."  |
> | 2@ 5'  | 3 | 0@ 41' 40." |
> #+TBLFM: $3=$1/$2
> 
> Maybe all that is needed is explicit mention of this syntax somewhere in
> the table section of the Org-mode manual.
> 
> The only remaining reason to support a %d:%d time format is that it is
> what I (and I expect most users) would first think of to represent time,
> and supporting such a format would allow time calculation in a table to
> "just work" -- meaning users could likely manipulate time without having
> to first look in the manual for the appropriate Calc format.
> 
> However as Carsten mentioned such an automatic translation of e.g.,
> =7:20= to =7@ 20'= would be a bit bold, and (as mentioned elsewhere) it
> would result in having to make some denomination decisions, namely does
> =7:20= convert to =7@ 20'= or =7' 20"=.
> 
> For now I've posted my `with-time' macro up to Worg.
> 
> Cheers -- Eric

Hi all,

just came back on this thread and was amazed what you guys did with it.. 
amazing.. havent tried the patch yet but the with-time macro is great. Now it 
is even easy to sum up a whole column of timevalues.

I use it like the following now:

| start | lunch |  back | leave |   sum |
|-------+-------+-------+-------+-------|
|  8:00 | 12:00 | 13:00 | 17:00 |  8:00 |
|  8:00 | 12:00 | 13:00 | 17:00 |  8:00 |
|-------+-------+-------+-------+-------|
|       |       |       |       | 16:00 |
#+TBLFM: @>$5='(with-time t (+ @2..@>>))

Thanks a lot (also for making it to org hacks : )
Martin