Improved algorithm for joining large files
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Join.vim - A vim plugin, that implements a different algorithm for joining
many lines.

I) Directory layout 
This repository contains the Join.vim plugin, the unit tests and the 
documentation. The current directory structure looks like this:


The subdirectory doc/ contains the documentation for the plugin.
The subdirectory plugin/ contains the Vim plugin and the unit-tests
are located below test/. In the test-directory there are files and
directories located:


expected/ and result/ are 2 scratch folders that will be created when
running They contain the expected and observed data from the
test cases, which are situated below source/. is a little
script, that runs the test-cases and compares the expected and observed
results. To run it, simply run make test from the toplevel directory.

II) Installation
This plugin comes as vimball, which makes it really easy to install it
into the right place. 
1) Edit Join.vba with your vim (:e Join.vim) 
2) From within vim, simply source the file (using :so %)
3) Restart vim to autoload the plugin and the documentation (:q)
4) Read the help at :h Join.txt 

III) Documentation
This plugin tries to implement a different method for joining lines. This is, 
because the :join command from within vim suffers from a serious performance 
issue, if you are trying to join many lines (>1000). 

This has been discussed on the vim development mailing list (see as well as on the vim 
user mailing list (see 

There has also been a patch proposed, to improve the algorithm used by :join. 
This patch is available at, but this 
means, you'll have to build and patch your vim manually (you can't use it with 
a prebuilt vim). 

Until this patch is accepted and incorporated into mainline vim, this plugin 
tries to improve the joining algorithm by the method mentioned in the user 
mailinglist above. It basically works by breaking up the join algorithm into 
smaller pieces and joining the smaller pieces together. This may have an 
impact on memory usage, though. 

For reference I include some timings, joining many lines: 

      Lines joined      :%join      |      :%Join 
        25.000           3,305s     |      0,240s 
        50.000          13,667s     |      0,336s 
       100.000          64,140s     |      0,588s 
       200.000         331,410s     |      1,431s 
     1.000.000            -[1]      |      7,419s 

[1] benchmarking was aborted after 53 Minutes (after which only about 480.000 
lines have been joined). 

Please also note, that using a substitute command does not prove to be faster. 
It also suffers from the performance impact. 

Also note, that really the best way to remove '\n' on a file with millions 
of lines is using tr: 

~$ tr -d '\n' <large_file >output_file 

2. Usage                                                          *Join-usage* 

                        Join [range] lines.  Same as "J", except with [!] 
                        the join does not insert or delete any spaces. 
                        The default behavior is to join the current line 
                        with the line below it. 

:[range]J[oin][!] {count} 
                        Join {count} lines, starting with [range] (default: 
                        current line |cmdline-ranges|).  Same as "J", except 
                        with [!] the join does not insert or delete any 

You should be able to use :Join as drop in replacement for :join. It behaves 
exactly like :join and understands it's syntax, with the exception of 1 point: 

1) :Join does not accept the use of [flags] as |:join| does. 

If you want the J command to call :Join, you can use something like: 
:nmap J :Join<CR> 
to have J call :Join in normal mode and 
:vmap J :Join<CR> 

3. Differences 

This plugin has been made to make :Join and :join behave almost identically. 
If there are further differences than those described at |Join-usage|, I am 
interested at any bug describing exactly what went wrong, so I can fix this. 
Please send any bug report to the mail address mentioned at the top of this 

# Vim-Modeline:
# vim: tw=72 spell spelllang=en