Running elisp conversion function in an Org table returns an error

Question

For a table I would like to convert the first column from decimal numbers to binary. The table looks so far like this:

|    .   |  . |         . |       . |     . |
|    .   |  . |         . |       . |     . |
|    .   |  . |         . |       . |     . |
|   1304 | 24 |         9 |      15 |     5 |
|   1305 | 25 |        10 |      15 |     5 |
|   1306 | 26 |        11 |      15 |     5 |
|   1307 | 27 |        12 |      15 |     5 |
|   1308 | 28 |        13 |      15 |     5 |
|   1309 | 29 |        14 |      15 |     5 |
|   1310 | 30 |        15 |      15 |     5 |
|   1311 | 31 |        16 |      15 |     5 |
|   1312 | 32 |        17 |      15 |     5 |
|   1313 | 33 |        18 |      15 |     5 |

For the conversion I found already a working function:

(defun binList(N)
  (cond 
   ((< N 1) '())
   ((= N 1) '(1))
   ((> N 1) (if(=(mod N 2) 0) 
            (append (binList(/ N 2)) '(0))
            (append (binList(floor(/ N 2))) '(1))))))

When I want to apply the TBLFM

+TBLFM: $1='(binList $1)

i just get errors ( I tried also to convert the 2. column and write into the first)

|      .   |  . |         . |       . |     . |
|      .   |  . |         . |       . |     . |
|      .   |  . |         . |       . |     . |
|   #ERROR | 24 |         9 |      15 |     5 |
|   #ERROR | 25 |        10 |      15 |     5 |
|   #ERROR | 26 |        11 |      15 |     5 |
|   #ERROR | 27 |        12 |      15 |     5 |
|   #ERROR | 28 |        13 |      15 |     5 |
|   #ERROR | 29 |        14 |      15 |     5 |
|   #ERROR | 30 |        15 |      15 |     5 |
|   #ERROR | 31 |        16 |      15 |     5 |
|   #ERROR | 32 |        17 |      15 |     5 |
|   #ERROR | 33 |        18 |      15 |     5 |

are there some further steps needed/ in between ?

Answer 1

Two problems:

• Table entries are strings. You need to convert the string "10" to the number 10 before passing it to your binList function.

• The binList function returns a list and AFAICT org has trouble converting it to a string.

Try the following:

 |  n |
 |----|
 |  1 |
 |  2 |
 |  3 |
 |  4 |
 |  5 |
 |  6 |
 |  7 |
 |  8 |
 |  9 |
 | 10 |
 #+TBLFM: $1='(binString (string-to-number $1))


 #+BEGIN_SRC emacs-lisp
   (defun binString(N)
     (cond 
       ((< N 1) "")
       ((= N 1) "1")
       ((> N 1) (if (= (mod N 2) 0) 
                   (format "%s0" (binString(/ N 2)))
                 (format "%s1" (binString(floor(/ N 2))))))))
 #+END_SRC

The logic of binString is identical to that of binList but it deals with strings instead.