Re: Calc: Multiply time (hours) with a float

[Karl Voit <devnull@Karl-Voit.at>]

* Michael Welle <mwe012008@gmx.net> wrote:
> Hello,

Hello Michael,

> Karl Voit <devnull@Karl-Voit.at> writes:
>
>> * Karl Voit <devnull@Karl-Voit.at> wrote:
>>> Hi!
>>>
>>> I do have following situation: I'd like to multiply a float with hours
>>> which results in an error, obviously. However, I was not able to find
>>> out how to do it.
>>>
>>> Minimal example with expected product:
>>> 
>>> | time [h:m:s] |   value | h * value |
>>> |--------------+---------+-----------|
>>> |     09:15:00 | 2.54321 | 23.524693 |
>>>  #+TBLFM: @2$3=$2*$1
>>
> do you really need the result to be in decimal notation? 

If I want to implement my original idea (see my original posting):
yes.

> If not, 
> #+TBLFM:@2$3=$2*$1;T would work. If you need decimal notation you have
> to provide your own function, I think.

So I wrote some Elisp code:

  (defun org-time-string-to-seconds (s)
    "Convert a string HH:MM:SS to a number of seconds.
     Omitted third element will be interpreted as MM:SS with missing hours."
    ;; test with:
    ;; (message (concat "result is: " (number-to-string (org-time-string-to-seconds "57:45:03"))))
    ;; (message (concat "result is: " (number-to-string (org-time-string-to-seconds "57:45"))))
    (cond
     ((and (stringp s)
       (string-match "\\([0-9]+\\):\\([0-9]+\\):\\([0-9]+\\)" s))
      (let ((hour (string-to-number (match-string 1 s)))
        (min (string-to-number (match-string 2 s)))
        (sec (string-to-number (match-string 3 s))))
    (+ (* hour 3600) (* min 60) sec)))
     ((and (stringp s)
       (string-match "\\([0-9]+\\):\\([0-9]+\\)" s))
      (let ((min (string-to-number (match-string 1 s)))
        (sec (string-to-number (match-string 2 s))))
    (+ (* min 60) sec)))
     ;;((stringp s) (string-to-number s))
     ;;(t s)
     )
    )

  (defun org-time-string-to-hours (s)
    "Convert a string HH:MM:SS to hours (float).
     When only two values given, they will be interpreted as MM:SS with missing hours."
    ;; test via:
    ;; (message (concat "result is: " (number-to-string (org-time-string-to-hours "57:45:03"))))
    ;; (message (concat "result is: " (number-to-string (org-time-string-to-hours "57:45"))))
    (/ (org-time-string-to-seconds s) 3600.0)
    )

... which is working:

| time [h:m:s] |   value | hours [float] |   product |
|--------------+---------+---------------+-----------|
|     09:15:00 | 2.54321 |          9.25 | 23.524693 |
#+TBLFM: $4=$2*$3::@2$3='(org-time-string-to-hours $1)

However, when I try to calculate the product in one step, I get an error:

| time [h:m:s] |   value | product |
|--------------+---------+---------|
|     09:15:00 | 2.54321 | #ERROR  |
#+TBLFM: @2$3='(* $2 (org-time-string-to-hours $1))

When I replace "$2" in TBLFM with an integer value, it works.

How can I calculate the product in /one/ step?

Thanks again!

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