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Uniq - Removing duplicate lines

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created 2004 · complexity intermediate · author Michael Geddes · version 7.0


The following command will sort all lines and remove duplicates (keeping unique lines):

:sort u

If you need more control, here are some alternatives.

There are two versions (and \v "verymagic" version as a variant of the second): the first leaves only the last line, the second leaves only the first line. (Use \zs for speed reason.)

g/^\(.*\)\n\1$/d
g/\%(^\1\n\)\@<=\(.*\)$/d
g/\v%(^\1\n)@<=(.*)$/d

Breakdown of the second version:

g/\%(^\1\n\)\@<=\(.*\)$/d
g/                     /d  <-- Delete the lines matching the regexp
            \@<=           <-- If the bit following matches, make sure the bit preceding this symbol directly precedes the match
                \(.*\)$    <-- Match the line into subst register 1
  \%(     \)               <-- Group without placing in a subst register.
     ^\1\n                 <-- Match subst register 1 followed the new line between the 2 lines

In this simple format (matching the whole line), it's not going to make much difference, but it will start to matter if you want to do stuff like match the first word only.

This does a uniq on the first word in the line (with the \v "verymagic" version included after), and deletes all but the first line:

g/\%(^\1\>.*\n\)\@<=\(\k\+\).*$/d
g/\v%(^\1>.*\n)@<=(\k+).*$/d

See alsoEdit

CommentsEdit

Here are some more Vim-native ways for removing duplicate lines. This time they don't have to be adjacent. Line order is preserved.

This one can be a bit slow. And the pattern would match a single empty line which would also be deleted. The part ":g/^m0<CR>" at beginning and end of the command maybe optional.

:nno \d1 :g/^/m0<CR>:g/^\(.*\)\n\_.*\%(^\1$\)/d<CR>:g/^/m0<CR>

This is faster. Uses mark l.

:nno \d2 :g/^/kl\|if search('^'.escape(getline('.'),'\.*[]^$/').'$','bW')\|'ld<CR>

Following uses a substitute to delete all repeated lines (leaving only the first line, while deleting following duplicate lines). This is a variation on the g//d method.

%s/^\(.*\)\(\n\1\)\+$/\1/
%s/\v^(.*)(\n\1)+$/\1/

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