Using Emacs Org Mode tables to calculate doses to buy

I got tired of manually calculating how many I needed to buy based on a daily protocol and how many I had in stock, so I wrote a little bit of Emacs Lisp to figure it out. You can specify the type, daily dose, start and end dates (inclusive; defaults to the last specified date if blank), and how many you have in stock.

First, define a table of this form, and give it a name.

#+NAME: input
| Type         | Per day |      Start |        End | Stock |
|--------------+---------+------------+------------+-------|
| Medication A |       2 | 2015-06-09 | 2015-06-16 |     5 |
| Medication B |       1 |            |            |     0 |
| Medication C |     0.1 | 2015-06-12 | 2015-06-16 |   0.2 |
Type Per day Start End Stock
Medication A 2 2015-06-09 2015-06-16 5
Medication B 1 0
Medication C 0.1 2015-06-12 2015-06-16 0.2

To call the code from the bottom of this post, use something like:

#+CALL: calculate-meds-needed(meds=input) :hlines yes :colnames yes
Type Total In stock Needed
Medication A 16 5 11
Medication B 8 0 8
Medication C 0.5 0.2 1

Here’s the code that processes it:

#+name: calculate-meds-needed :var meds=meds :colnames yes :hlines yes
#+begin_src emacs-lisp
(let (start end)
  (append
   (list (list "Type" "Total" "In stock" "Needed"))
   (list 'hline)
   (sort (delq nil (mapcar
                    (lambda (row)
                      (unless (or (eq row 'hline) (string= (elt row 0) "Type"))
                        (let (total)
                          (setq start (if (string< "" (elt row 3)) (elt row 3) start)
                                end (if (string< "" (elt row 2)) (elt row 2) end)
                                total (* (elt row 1)
                                         (- (calendar-absolute-from-gregorian (org-date-to-gregorian start))
                                            (calendar-absolute-from-gregorian (org-date-to-gregorian end))
                                            -1)))
                          (list
                           (elt row 0)
                           total
                           (elt row 4)
                           (max 0 (ceiling (- total (elt row 4))))))))
                    meds)) (lambda (a b) (string< (car a) (car b))))))
#+end_src
  • Mehmet Ergun

    I’d love to use this to learn a little bit of lisp! Could you by any chance be able to somehow show which lisp code produces which cell in the table produced by the #+CALL? Thanks :)