Re: Keep-only-column

[Marc Tfardy]

Marc Tfardy schrieb:
> weber wrote:

>  >> Quite frequently I paste stuff which is space-separated.
>  >> I would really like a function that would let me select a region and
>  >> keep only a column, deleting all the rest.
>  >> Anyone knows how I could implement something like this?
>  >> I can do it with regexps, but then I have to come up with a new one
>  >> every time...
>  >> TIA
>  >> HS
>  >
>  > I think the format of "stuff" can't be understood from above :) Here
>  > it is:
>  >
>  > variable BLABLA  =     438438
>  > variable LABLAC  =     312
>  > variable DAUSH  =     43538
>  >
>  > Apply to that region: keep-only-column 2 makes it:
>  > BLABLA
>  > LABLAC
>  > DAUSHD
>
>
>
> Here my draft. Probalby inefficient, but it does the job.
>
>
> (defun trim-rectangle (start end)
>   "Trims region to rectangle."
>   (interactive "r")
>   (save-excursion
>     (let ((offset 0)
>           (width 0)
>           (lines (count-lines start end))
>           (i 0))
>       (goto-char start)
>       (beginning-of-line)
>       (setq offset (- start (point)))
>       (goto-char end)
>       (beginning-of-line)
>       (forward-char offset)
>       (setq width (- end (point)))
>       (goto-char start)
>       (while (< i lines)
>         (beginning-of-line)
>         (delete-region (point) (+ (point) offset))
>         (forward-char width)
>         (delete-region (point) (line-end-position))
>         (end-of-line)
>         (forward-char)
>         (setq i (+ i 1))))))

And now slightly tuned version with extra feature - deleting
trailing whitespaces in the region:

(defun trim-rectangle (start end &optional delete-whitespace)
  "Trims region to rectangle. With \\[universal-argument] deletes 
trailing whitespaces."
  (interactive "*r\nP")
  (save-match-data
    (save-excursion
      (let ((offset 0)
            (width 0)
            (lines (count-lines start end))
            (curren-point 0)
            (i 0))
        (goto-char start)
        (setq offset (current-column))
        (goto-char end)
        (setq width (- (current-column) offset))
        (goto-char start)
        (while (< i lines)
          (beginning-of-line)
          (setq current-point (point))
          (delete-region current-point (+ current-point offset))
          (forward-char width)
          (delete-region (point) (line-end-position))
          (if delete-whitespace
              (progn
                (beginning-of-line)
                (if (re-search-forward "[ \t]*$" (line-end-position) t)
                    (delete-region(match-beginning 0) (match-end 0)))
                (end-of-line)))
          (forward-char)
          (setq i (+ i 1)))))))



regards

Marc