I have files such as these:

+ Something
+ Another thing
+ One more thing
+ Something else
+ And one more thing

In the above, the numbers represent time in HHMM format. I want to transform it to:

0010 + Something
0020 + Another thing
0030 + One more thing
0115 + Something else
0200 + And one more thing

I will explain the transformation in the above example:

  • between 0030 and 0200 there are 3 lines. And time difference between 0000 and 0030 is 30 minutes. So each item below 0030 gets a 10 minutes increment starting from 0000. And thus the 3 new timestamps are 0010, 0020 and 0030 respectively.

  • similarly between 0200 and 0230 there are 2 lines. And the time difference between 0030 and 0200 is 90 minutes. So each item below 0200 gets 45 minutes increment starting from 0030. So the 2 new timestamps are 0115 and 0200 respectively.

I have made some progress in writing an elisp-macro for this transformation task:

  1. I could modify the answer to this emacs.stackexchange post to compute the time difference between times.

  2. I could write a function that takes in time and minutes elapsed to print new time after adding elapsed minutes to time.

  3. Now the only thing that I need to complete my recipe is: the number of items between two consecutive HHMM patterns so that I can split the difference of time evenly over the items.

  4. Lastly I plan to wrap up all the above inside a (while (search-forward-regexp "pattern" nil :noerror) to apply the above macros to everywhere applicable inside the file.

Here is the summary of my failed attempts so far:

I recorded a keyboard macro to mark the region between two consecutive HHMM pattern and then I am trying to use (count-lines start end). However I get the error:

Symbol's value as a variable is void: start

Here is my code snippet for this attempt:

(defun timesheet-fill-times ()
  (let (diff lines)
      (setq diff (timesheet-time-diff))
      (setq lines (count-lines start end))
      (message "%d diff %d lines" diff lines)

where timesheet-time-diff is my elisp macro to compute time difference between consecutive patterns and timesheet-mark-lines is my recorded keyboard macro to mark the relevant region. I tried to modify the function definition to: (defun timesheet-fill-times (start end) ;; rest of code ). Now the error becomes:

Wrong number of arguments

However, strangely, the following works alright: I have defined this function:

(defun my-count-lines-region (start end)
   (interactive "r")
   (message "%d"
       (count-lines start end)))

So if I keep my cursor on + after 0030 and do M-x timesheet-mark-lines RET M-x my-count-lines-region RET I get 3 as expected. And similarly with the cursor on + after 0200 I get 2 as expected.

My other approach I thought of was that: I can match for the pattern HHMM - some lines - HHMM by using something like this:

(re-search-forward (concat "^\\([0-2][0-9]\\)\\([0-5][0-9]\\)"
                            ) nil :noerror)

Is there someway I can count the number of newline characters in that match?

I have tried my best but I feel stuck. Please advice.

  • My guess is that it would be simpler to write this in python (or perl if you are so inclined).
    – NickD
    Commented Jul 3, 2021 at 3:10
  • Sure, great suggestion. But, I am trying to learn lisp. And it feels so great when something works! Commented Jul 3, 2021 at 4:33
  • You will not learn much lisp of this, but you could use count-words-region. Despite its name, it also gives you the number of lines is the region. Commented Jul 3, 2021 at 5:17
  • 1
    You can get the match with match-string 0. You will find what exactly this pattern matches to (which does not include multiple lines). Otherwise you could split-string on \n and get the length of the resulting list. You can test your regexp with the regexp-builder. Commented Jul 3, 2021 at 6:02

2 Answers 2


THIRD EDIT (added after @Inspired_Blue's answer)

@Inspired_Blue I did not try to completely follow and understand your answer. But as a matter of feedback, I will post here my way of solving the problem. While incidentally it inserts the correct times, you should still add functions to get the correct times for the general case.

I strongly recommend you to get familiar with edebug as it is only a really tiny bit of reading, while it will greatly boost your productivity. Then practice how to use edebug, while using it for reading my solution.

In short, in my solution I first parse the buffer into the following list (call se-answer interactively on your original text to see a pretty printed version of the list), where the car of each element is a pair (cons) with the start and end times, and the cdr forms a list containing the lines (the length of this list, effectively counts the number of lines between consecutive matches, providing an answer to your question).

(((0 . 30))
 ((30 . 200) "+ Something\n" "+ Another thing\n" "+ One more thing\n")
 ((200 . 230) "+ Something else\n" "+ And one more thing\n"))

Subsequently I format the list 'back' to your transformed text using a "list-eater" (term used in the books "Land of lisp" and "Realm of racket")

;; define handy macro for pretty printing
(defmacro parse-print (data &optional stream mode)
  "Return value but pretty print when called interactively.
Optionally set STREAM (see `pp'). If STREAM is a buffer then
optionally set MODE for buffer (for syntax highlight)."
  `(if (not (called-interactively-p))
     (pp ,data ,stream)
     (when (bufferp ,stream))
     (pop-to-buffer ,stream)
     (when ,mode
       (funcall ,mode))))

(defun se-answer ()
  ;; to prevent infinite loop first delete all trailing blank lines and
  ;; whitespace, and if exist final newline
  (goto-char (point-max))
  (when (bolp)
    (delete-backward-char 1))
  (goto-char (point-min))
  ;; parse buffer
  (let (blocks) ;; we designate blocks for each part between a start- and end-time
    (while (not (eobp))
      ;; use only this while loops body for single block (e.g. for your keyboard
      ;; macro)
      (let (lines ;; per block we collect (push) the text lines in (to) a list
            (start-time (thing-at-point 'number))) ;; also we collect the start-time
        (while (not (thing-at-point 'number))
          (push (thing-at-point 'line t) lines)
        (push (cons (cons start-time (thing-at-point 'number))
                    (nreverse lines)) ;; and collect (push) the start- and end-time plus
              blocks)                 ;; the lines in the block in (to) the list of blocks
    (unless (called-interactively-p)
    ;; NOTE that you can call this function/command interactively to see the
    ;; pretty printed list.
    (parse-print (nreverse blocks) (get-buffer-create "parsed-list") 'emacs-lisp-mode)))

(defun insert-transformed-text (parsed-buffer)
  (interactive (list (se-answer)))
  ;; First an exit condition for. A list eater 'eats' the elements of the list
  ;; so we exit when there is only one element left (which can optionally get
  ;; inserted to the buffer).
  (if (not (cdr parsed-buffer))
      (if (y-or-n-p "Include final time?")
          (insert (format "%s" (cdaar parsed-buffer)))
  (let* ((n (length (cdadr parsed-buffer)))
         (int-size (/ (- (cdaar parsed-buffer) (caaar parsed-buffer)) n)))
    (let ((time (+ (caaar parsed-buffer) int-size)))
      (dolist (x (cdadr parsed-buffer))
        (insert (format "%s %s" time x))
        (setq time (+ time int-size)))))
  ;; By passing back the 'tail' of the list, the function 'slowly eats' the
  ;; list.
  (insert-transformed-text (cdr parsed-buffer))))

Find a buffer with C-x C-f and give it some name ending with the .el (this opens a buffer in emacs-lisp-mode), paste and load the code in that buffer. Then open a scratch buffer in a split screen and paste your original text/list. Then instrumentalize the insert-transformed-text (or the se-answer) function/command (see edebug), and finally in the scratch buffer (with ONLY your original text) run the command M-x insert-transformed-text.

Have fun!


I see now that you already found count-lines (I read over it). So the (interactive "r") provides your function with region-beginning and region-end as its arguments (see here and here).

I've added a comment to answer your question about lines in the regexp match. But I would strongly advise not to approach the problem in this way.


Programmatically, count-words-region does not fulfil your needs directly. But by inspecting the function you will find the function count-words--message, from which you get another answer by inspecting its code (simpler than my provided solution).


As it seems you want to mark the region, I provided a simplest answer as a comment. Now I am not sure what you ask exactly, but more programmatically, I would propose something as follows:

(defun se-answer ()
  (let ((start-time (thing-at-point 'number))
        (start-line (string-to-number (cadr (split-string (what-line))))))
    (re-search-forward "^[0-9]+")
    (let ((end-time (thing-at-point 'number))
          (end-line (string-to-number (cadr (split-string (what-line))))))
      (message "start-time %s\nstart-line %s\nend-time   %s\nend-line   %s\nnum lines: %s"
               (- end-line start-line 1)))))

@dalanicolai's se-answer function (see here), I believe, is superior to my solution as mine uses regular expressions and hence is possibly slower. Hence I accept his solution as the answer to this question.

However I will share my solution here as well (for anyone who may learn something new from code snippets on stackexchange, like I do):

(defun my-count-occurences (regex string)
  (my-recursive-count regex string 0))

(defun my-recursive-count (regex string start)
  (if (string-match regex string start)
      (+ 1 (my-recursive-count regex string (match-end 0)))

(defun timesheet-count-items ()
  (let (match diff lines)
      (if (re-search-forward (concat "^\\(\\(.\\|[\n]\\)*?\\)"
                     ) nil :noerror)
      (my-count-occurences "\n" (match-string 1))

(defun timesheet-time-diff ()
  (let (begin-hh begin-mm end-hh end-mm diff)
      (if (re-search-backward (concat "^\\([0-2][0-9]\\)\\([0-5][0-9]\\)"
                                      ) nil :noerror)
            (setq begin-hh (string-to-number (match-string 1))) 
            (setq begin-mm (string-to-number (match-string 2))) 
            (setq end-hh (string-to-number (match-string 5))) 
            (setq end-mm (string-to-number (match-string 6)))
            (setq diff (- (+ end-mm  
                 (* 60 end-hh))
              (+ begin-mm 
                 (* 60 begin-hh))))
        (list begin-hh begin-mm diff)

(defun timesheet-time-add (hh mm de)
  (let (M h m O)
    (setq M (+ (* 60 hh) mm de))
    (setq h (/ M 60))
    (setq m (% M 60))
    (setq O (concat (format "%02d" h)(format "%02d" m)))

(defun timesheet-fill-time ()
  (let (temp count diff step start-hh start-mm delta)
      (setq count (timesheet-count-items))
      (setq temp (timesheet-time-diff))
      (setq start-hh (nth 0 temp)
        start-mm (nth 1 temp)
        diff (nth 2 temp))
      (setq step (/ diff count))
      (while (> count 0)
    (setq count (- count 1))
    (setq delta (- diff (* count step)))
    (insert (concat (timesheet-time-add start-hh start-mm delta)
            " "))

(defun timesheet-process ()
  (goto-char (point-min))
  (while (re-search-forward "
0-9]\\)" nil t)
    (backward-char 1)
  (goto-char (point-min))
  (while (search-forward-regexp "
" nil t) (replace-match "
" t nil))

So to compare my solution with @dalanicolai's solution:

  1. I solve for the entire transformation as in the example of my question.
  2. Clearly @dalanicolai's solution is more elegant and pithy.
  3. I will have to adapt @dalanicolai's solution to my needs to carry out the entire transformation (which I plan to do sometime soon and add as an edit to my answer).
  4. My files have about 400-600 lines. And even my solution runs almost instantaneously.

Lastly, if you happen to read my code and are kind enough to offer me feedback, please do. As I have just started learning lisp, I will value such things immensely!

  • FYI, I have once more edited my answer Commented Jul 3, 2021 at 11:16
  • Many thanks! Very helpful. Commented Jul 3, 2021 at 13:51

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