Question

I have a single line text file of csv values

I would like to able to ‘pretty-print’ the file to span multiple lines to make it more readable

The 1st no. represents the no. of csv values in the next section and so on

e.g.

3,1,2,3,3,4,5,6

would be converted to:

3,1,2,3
3,4,5,6

I know a little about making macros, e.g.

C-x (
C-s RET ,
C-x )

using this I can do:

C-u 3 C-x e to move 3 csv values along

My sticking point is how to use the value from file to paste into the arg to C-u

maybe I should be using an e-lisp function instead as its a function I would like to ‘save’ for continual use across emacs sessions. Is it possible to save macros as such?

any ideas gratefully received

Answer 1

I find elisp easier to think about than keyboard macros. How about this:

(defun csv-line-breaks ()
  (interactive)
  (while (search-forward "," nil t 
                         (1+ (string-to-number (thing-at-point 'word))))
    (delete-char -1)
    (insert "\n")))

(global-set-key (kbd "C-c b") 'csv-line-breaks)

With this in your .emacs (or just evaluate the code in your scratch buffer), you put point at the beginning of the line, then hit C-c b to break the line up into the chunks you want.

What this does:

1. Looping over the buffer until it runs out of values, and for each loop:
2. Read the first value. (thing-at-point 'word) grabs anything it finds between whitespace of punctuation (more or less).
3. Convert the value, which is actually a string, into a number
4. Add one to that number, and move forward that many commas
5. Delete the previous comma
6. Insert a new line