Control lines

[Contro]

I would like

a text editor able to control lines in special ways.

By example :
1. Maintain lines 1,5,9,13,17,21, and so on until the final of the txt file.
That is a aritmetic progression of reason equal to 4, where the first is 1.
Delete the rest of lines.

2. Any other criteria over the lines.

Note : i am only looking now for the 1. . It's the important case to me now.

Best Regards
Happy New Year

[Edvard]

Textpad 5 I found to be particularly useful regarding line manipulation.  You can 'bookmark' lines you want to keep and then "Delete unselected lines".  I think Notepad++ can do similar, but it's somewhere else in the menu.  To select the lines you want programatically, Textpad has extensive support for macros (almost as good as scripting):
http://www.textpad.com/add-ons/macros.html
and Notepad++ can be scripted with Python via the Python plugin:
http://www.sivachandran.in/2012/04/scripting-notepad-with-python.html

Sorry I don't have a more definitive answer, hope it helps though. 

[Contro]

Thanks a lot Edvard and happy new year 2014.

At the present moment I am applying the wonderful script from Skwire
http://www.donationcoder.com/forum/index.php?topic=36898.0

I'll take a look to both programs. At the present I know notepad++ that i am using as an alternative to PSPad where i find more confortable.

Best Regards