How to delete nonconsecutive lines in text using RegEx?

Question

I use the following expression in Notepad++ to delete duplicate lines:

^(.*)(\\r?\\n\\1)+$ 

The problems are:

1. It is only for

Answer 1

Since no one is interested, I will post what I think you need.

delete duplicate lines in a text that contains space, and that are nonconsecutive

I assume you have text having, say duplicate lines My Line One and some text and My Line Two and more text:

My Line One and some text
My Line One and some text
My Line Two and more text
My Line One and some text
My Line Two and more text

These duplicate lines are not all consecutive (only the first two).

So, you can remove duplicate lines by running this search and replace:

^(.+)\r?\n(?=[\s\S]*?^\1$)

Replace with empty string.

Regex note: ^ and $ are treated as line start/end anchors by default, so we only match one line and capture it with ^(.+)$. Then we match the newline symbol (any OS style) with \r?\n. The look-ahead (?=...) checks if there is any text (with [\s\S]*?) after our line under inspection with the same contents (with the ^\1$ where \1 is a backreference to the line text captured).