Practice With Vim (I)

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What would be the easiest way to remove all but one word from the end of each line in Vim?

Today, I found a challenge on vimgolf and thought it might be interesting to share my solutions.

Here is the original file

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abcd 1 erfg 7721231
acd 2 erfgasd 324321
acd 3 erfgsdasd 23432
abcd 5 erfgdsad 123556

Here is the desired result:

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7721231
324321
23432
123556

The challenge is quite straightforward, delete all but the last characters in the file. I found several ways to tackle this challenge, so let me show you all:

Take 1: Use macro only

Record a macro, and play it back, so the keystrokes would be

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qa $bd0j q [email protected] <cr>

qa starts recording macro to register a
$ move cursor to the end of the line
d0 means *d*elete to the beginning of the line
j move cursor down
q finish macro
[email protected] repeat the macro in register a 4 times

Take 2: Use regex and %norm

It's quite obvious that all we want to keep from the original files are the numbers. So the regex would be simple to come up with, like something as simple as /\d\+$<cr> will do. Once you type this into vim, all the numbers at the end of the line will be highlighted. Next you can do: 

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:%norm dn <cr>

% means applying to the whole file,
norm means in execute following command in normal mode
dn means *d*elete to *n*ext match

Take 3: No regex pure %norm

This is the fastest way I can come up with, still, not as fast as the top answers on Vimgolf but it is decent in my opinion. Being slightly different from the option above, it is still using %norm though:

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%norm $bd0 <cr>  

% means applying to the whole file,
$ move cursor to the end of the line
d0 means *d*elete to the beginning of the line

Takeaways:

  • norm is a quite powerful, and can be used to achieve complex stuff that can be otherwise achieved through a macro.
  • d the delete command is useful in many unexpected ways, besides dn and d0 command mentioned above which deletes to the next match and deletes to the beginning of the line respectively. An additional useful variation of d command is d4/x where 4/x meaning 4th occurrence of x.