Re: Time calculation: vsum?

[Michael Markert <markert.michael@googlemail.com>]

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Hi Christian,

On 17 Jul 2011, Christian Moe wrote:
> Hi,
>
> Time calculations don't seem to work with vsum (or vmean).
>
>
> |    Time |
> |---------|
> | 1:06:00 |
> | 0:52:30 |
> | 2:00:00 |
> |---------|
> |       3 |
> #+TBLFM: @5$1=vsum(@I..@II);T
>
>
> Am I doing something wrong?

Yes, `vsum' works just on numbers, not times.

> Could this be made to work?
Here's a elisp function that does what you want (assuming it's
hours:minutes:seconds -- if not tweak the numbers):

#+begin_src elisp
(defun h-m-s-vsum (times)
  (loop for (h m s) in (mapcar (lambda (time)
                            (mapcar #'string-to-int
                                    (split-string time ":" 'omit-nulls)))
                               times)
       collect (+ (* 3600 h) (* 60 m) s) into seconds
       finally (return (let* ((second-sum (apply #'+ seconds))
                              (seconds (let ((s (% second-sum 60)))
                                         (decf second-sum s)
                                         s))
                              (minutes (let ((m (% second-sum 3600)))
                                         (decf second-sum m)
                                         (truncate (/ m 60))))
                              (hours (/ second-sum 3600)))
                         (format "%s:%s:%s" hours minutes seconds)))))
#+end_src elisp

The table has to be

|    Time |
|---------|
| 1:06:00 |
| 0:52:30 |
| 2:00:00 |
|---------|
| 3:58:30 |
#+TBLFM: @5$1='(h-m-s-vsum '(@I..@II))

Hope that helps.
Maybe there is an easier way. I hope there is ;)

Michael

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