Notepad++ offers several ways to remove duplicate lines from a text file, ranging from built-in features to regular expression-based replacements. This tutorial will explore these methods, allowing you to choose the best approach for your needs.
1. Using the Built-in "Remove Duplicate Lines" Feature (Notepad++ v8.1 and later)
The simplest method, available in Notepad++ version 8.1 and newer, is to use the dedicated “Remove Duplicate Lines” feature.
- Navigate to Edit > Line Operations > Remove Duplicate Lines.
- Notepad++ will scan the entire file and remove all but the first occurrence of each unique line.
This approach is the most straightforward and requires no configuration or prior sorting of the file.
2. Removing Consecutive Duplicate Lines (Notepad++ v7.8 and later)
If your duplicate lines are already grouped together consecutively, you can use a streamlined feature available in Notepad++ versions 7.8 and beyond.
- Navigate to Edit > Line Operations > Remove Consecutive Duplicate Lines.
This removes immediately adjacent duplicate lines, leaving only a single instance of each consecutive sequence. This is significantly faster if your data is already grouped.
3. Removing Duplicate Lines Using Regular Expressions (All Versions)
For more complex scenarios, or if you are using an older version of Notepad++, you can leverage Notepad++’s powerful regular expression search and replace functionality. This approach doesn’t require any sorting.
- Open the Replace dialog (Ctrl+H).
- Ensure the Search Mode is set to Regular expression.
- Also, check the . matches newline option. This is crucial for handling multi-line documents.
The regex pattern to use is: ^(.*?)$\s+?^(?=.*^\1$)
^: Matches the beginning of a line.(.*?): Matches any character (.) zero or more times (*), but as few as possible (?). This captures the entire line. The parentheses create a capturing group, allowing you to reference the matched line later.$: Matches the end of the line.\s+?^: Matches one or more whitespace characters (including newline characters) followed by the start of the next line. This effectively removes the newline(s) after the matched duplicate line.(?=.*^\1$): This is a positive lookahead assertion. It checks if the following lines contain the same text as the captured line (referred to by\1). If the assertion is true (i.e., a duplicate line exists), the match is confirmed.
Leave the Replace with field empty. This will effectively remove the duplicate line and the whitespace characters following it.
4. Removing Duplicate Lines with TextFX Plugin (Older Versions)
While less necessary now due to built-in features, older Notepad++ versions relied on the TextFX plugin.
- Install TextFX: Download the TextFX plugin from https://sourceforge.net/projects/npp-plugins/files/TextFX. Place the downloaded
.dllfile in your Notepad++ plugins directory (usuallyC:\Program Files\Notepad++\plugins). - Sort and Remove: Go to TextFX > TextFX Tools. Check the sort outputs only unique… checkbox. Then, select the text you want to process (Ctrl+A to select all) and click sort lines case sensitive or sort lines case insensitive depending on your needs. This will sort the text and simultaneously remove duplicate lines.
Choosing the Right Method
- For Notepad++ v8.1 and later, the built-in Remove Duplicate Lines is the simplest and fastest option.
- If your duplicate lines are already consecutive, Edit > Line Operations > Remove Consecutive Duplicate Lines is the most efficient.
- Regular expressions provide a flexible solution for any Notepad++ version, but require understanding of regex syntax.
- The TextFX plugin is useful for older Notepad++ versions but is no longer necessary with built-in functionality.