Prepending a character followed by the line number to every line

I'm hand-editing CNC Gcode text files and need a way to reference locations in the file and on the toolpath.

I want to modify every line in the text file so that it begin开发者_如何学Pythons with the the upper case letter N followed by the line number, incremented in tens for each successive line, then a whitespace followed by the original text on that line. How can I do this in Vim?

I'm not sure about vi, but (since you're using the vim tag) Vim allows you to accomplish your task as follows:

1. Adjust the first line by hand (insert a N10 at the beginning of the line), then put the cursor at the beginning of the next line.

2. Press qb to start recording a macro (the b names the register used to store the macro; feel free to use a different letter -- and definitely do use a different letter if you've got something useful stashed away in b).

3. Move the cursor upward to the beginning of the previous line (which you have adjusted by hand). Press v to start visual selection mode, then f to move the cursor to the next space on the line (if you use a single space as your whitespace separator, that is; adjust this step if you're using a tab or multiple spaces).

4. Press y to yank the selected text. This will also remove the visual selection.

5. Move the cursor to the beginning of the next line. Press P to insert the previously yanked text before the cursor, that is, on the very beginning of the line.

6. Move the cursor to the numeric part of the line header. Press 10 C-a (1, 0, control + A) to increment that number by 10.

7. Move the cursor to the beginning of the next line. Press q to stop recording the macro.

8. Press 10000000 @b to execute the macro 10000000 times or until it hits the end of the file. This should be enough to take care of all the lines in your file, unless it is really huge, in which case use a bigger number.

...or use Vim to write a simple script to do the job in whichever language you like best, then run it from a terminal (or from withing Vim with something like :!./your-script-name). ;-)

The following command will prepend ‘N<line number * 10>’ to every line:

:g/^/exe 'normal! 0iN' . (line('.')*10) . ' '

You can do it easily in Vim with this:

:%s/^/\=line(".")*10 . " "/

This replaces the start of every line with the result of an expression that gives the line number times ten, followed by a space.

I have not timed it, but I suspect it might be noticeably faster than the other Vim solutions.

Cheating answer:

:%!awk '{print "N" NR "0", $0}'

There are two ways to implement that without resorting to external tools: via a macro or by using Vimscript. In my opinion, the first way is a little cumbersome (and probably not as effective as the solution listed below).

The second way can be implemented like this (put the code into your .vimrc or source it some other way):

function! NumberLines(format) range
    let lfmt = (empty(a:format) ? 'N%04d' : a:format[0]) . ' %s'
    for lnum in range(a:firstline, a:lastline)
        call setline(lnum, printf(lfmt, lnum, getline(lnum)))
    endfor
endfunction

The NumberLines function enumerates all lines of the file in a given range and prepends to each line its number according to the provided printf-format (N%04d, by default).

To simplify the usage of this function, it is convenient to create a command that accepting a range of lines to process (the whole file, by default) and a optional argument for the line number format:

command! -range=% -nargs=? NumberLines <line1>,<line2>call NumberLines([<f-args>])