deleting lines from a text file

[tom]

howdy guys,



I have a text file, and I want to delete all the lines before a certain line, and after a certain line.

Code Select Expand

(set 'a (parse (read-file "chapter-1.txt") "n"))

(a 22) happens to be "-------"

I want (a 24) back to (a 0) deleted.



I need to find another string, at whatever position, and delete to the end of the file.



What's the best way to do this?



Thanks!

[newdep]

I would use 'Currentline , 'Seek and 'Search

[m35]

So you have a text file like this?

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Line
   1 <some>
   2 <some>
    ...
  21 <some>
  22 -------
  23 <some>
  24 <some>
  25 <some>
    ...
   n "another string"
    ...
 eof

You want to remove lines 1 to 24, then find "another string" and delete from there to the end of the file?



After your line of code, something like this might do the trick (UNTESTED!)

Code Select Expand

(set 'a-rest (join (slice a 24) "n"))
(slice a-rest 0 (find "another string" a-rest))

As newdep said, you could also perform this task using such functions as (read-line), (current-line), (seek) and (search).

[cormullion]

You can remove a line:

Code Select Expand

(replace {-------} f)



or empty a numbered line with an empty string (and clean it later):

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(nth-set (f 4) "") ; line 4, 0-based
(clean empty? f)

or empty a line containing a string pattern

Code Select Expand

(nth-set (f (find "line 4" f 0)) "")

or empty a sequence of lines that contain a string

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(println f)
(dolist (i (ref-all "-------" f))
  (nth-set (f i) ""))

or make a new list by extracting a sequence of line numbers starting at a matching line:

Code Select Expand

(select f (sequence (find "line 4" f 0) (length f)))

(lots of scope with select, with the list-selection...)



It might depend on how big your file is to start with, but you probably won't notice too many problems with a 'chapter'..

[tom]

What is the f ?

[cormullion]

:-) a list of strings. You called it 'a'.