Can Vim write incremental lines? i.e. on each line A becomes B, and 1 becomes 2

Question

I wanted to write this:

A = mapping[0]
B = mapping[1]
C = mapping[2]
D = mapping[3]
E = mapping[4]
F = mapping[5]
G = mapping[6]
H = mapping[7]
I = mapping[8]
J = mapping[9]
K = mapping[10]
L = mapping[11]
M = mapping[12]
N = mapping[13]
O = mapping[14]
P = mapping[15]
Q = mapping[16]
R = mapping[17]
S = mapping[18]
T = mapping[19]
U = mapping[20]
V = mapping[21]
W = mapping[22]
X = mapping[23]
Y = mapping[24]
Z = mapping[25]

I ended up using LibreCalc, putting the different parts in different cells, adding the letters and numbers, concatenating the results and pasting the lot back into Vim.

I appreciate that what I wanted to write is awful code. I'm studying Python at the moment and have been trying to avoid going to find information myself that I know will be covered later in the course I'm following (http://interactivepython.org/).

The quickest way I knew of to do this in vim was to type something like

A = mapping[0] <ESC> hh <CTRL>+<V> BBh y $ o B <ESC> y 1] <CR>

I know vim is very powerful (I've been using it for a couple of weeks, am really enjoying it).

Would it have been possible to write what I wanted to with some vim command?

Answer 1

While it can be done with scripting, if you have a very recent version of Vim (e.g. the one in Arch Linux), you can use g Ctrl-a to increment a visual block. In your case:

1. Write the original line: A = mapping[0] Esc
2. Yank line and put 25 copies of it below: yy25p
3. Visually select the column containing the 0 char (block selection, using Ctrl-v), excluding the 0 from the 1st line (so you end up with a column containing the last 25 zeroes), then increment them with g Ctrl-a.
4. Apply the same method for the column containing A.

(Note: As comments show, one needs to add alpha to the nrformats options, in order to be able to increment letters, e.g.: set nrformats+=alpha.My vimrc has: set nrformats=hex,alpha, thus disabling octal and binary increment, which I don't use)

Answer 2

I prefer the visual increment solution that @VanLaser used (See :h v_CTRL-A). However I will show this can be done via macro as well.

Start with:

A = mapping[0]

Record the following keypresses into a macro of your choice (e.g q):

yyp:set nrformats+=alpha<cr><c-a>:set nrformats-=alpha<c-a>

This will duplicate the line and then increment the first character (e.g. A) and then increment the number portion. Run this macro 24 times and you are done, e.g. 24@q.

• qq - start recording into register q
• yyp - duplicate the line
• :set nrformats+=alpha<cr> - 'nrformats does not have alpha by default
• <c-a> - With alpha we can now increment letters
• :set nrformats-=alpha<cr> - remove alpha from 'nrformats'
• <c-a> - increment the next number
• q - stop recording
• 24@q - replay macro in register q 24 times

For more help see:

:h q
:h @
:h yy
:h p
:h 'nrformats'
:h :set
:h CTRL-A
:h v_CTRL-A

Answer 3

Fine answers already provided, I wouldn't have thought to go about it as nicely. I would have typed out all the letters on a single line and then introduced text and line break with an expression substitution (using line number for incremental number), something like

iABCDEFGHIJKLMNOPQRSTUVXYZ<Esc>:s/./\=submatch(0)." = mapping[".line('.')."]\n"/g

Answer 4

Almost always when doing something like this, I choose to use :substitute over macros. Especially the capability to evaluate expression in replacement when starting with \= makes it often possible (see :h sub-replace-special).

Once you have empty lines in place (25i<Enter><Esc>), you can use command

:1,26s/^/\=nr2char(line('.')+64) . ' = mapping[' . (line('.')-1) . ']'

the necessary sequences are generated using current line ('.' argument) number returned by function line(), and using nr2char() to convert decimal numbers to ASCII equivalents (65 = A). Necessary strings are concatenated using .

Answer 5

You can always try to use the operating system...

:r ! perl -E 'for(A..Z){say "$_ = mapping[", ord($_)-64 ,"]"}'