Consider the following Vim ex command,
:let i=1 | '<,'>g/^/ s/^\ *-/\=i/ | let i+=1
It replaces the heading dash with ordered number in selected lines.
I don't understand why this command works as a loop from the first line to the last line of the selected lines. That is, how g can repeat let i+=1 over and over again.
The pattern of a global command is:
:range g[lobal][!]/pattern/cmd
The global commands work by first scanning through the [range] of of the lines and marking each line where a match occurs. In a second scan the [cmd] is executed for each marked line with its line number prepended. If a line is changed or deleted its mark disappears. The default for the [range] is the whole file. (see http://vimregex.com/#global for more details)
Now let's analyse
:let i=1 | '<,'>g/^/ s/^\ *-/\=i/ | let i+=1
step by step.
let i=1 is a single command executed setting the basic number for the loop. We can just execute it alone at the very beginning. Then '<,'>g/^/ s/^\ *-/\=i/ | let i+=1 looks a little more like a global command.
'<,'>g defines the range. '< represents the first line and '> represents the last line of the selected area. (:help '< for more details)
^ of course matches every line in range.
s/^\ *-/\=i/ | let i+=1 is the [cmd], the number of times it will be executed equals to the number of lines in the selected area, and this is the most important reason why the loop took place.
The part before | is a typical substitute command :range s[ubstitute]/pattern/string/ (see http://vimregex.com/#substitute for more details)
^\ *- matches 0 or more whitespace followed by a dash at the beginning of a line. We substitute \=i for this pattern. (:help :s\= for more details)
After s/^\ *-/\=i/, let i+=1 is executed. Then the next line, ... , till the last line of selected area.
For better understanding that s/^\ *-/\=i/ | let i+=1 is a [cmd] as a whole, we can change the order of the two [sub-cmd], obtaining let i+=1 | s/^\ *-/\=i/. But for the same effect, let i=0 at the very beginning is essential.
This is the general pattern of a :global command:
:g/foo/command
Because everything after the second separator is considered as one command, the counter is incremented each time the command is executed: one time for each matching line.
Related
I have a file that looks like:
this name
this age
Remove these lines and space above.
Remove here too and space below
Keep everything below here.
I don't want to hardcode 2 as the number of lines containing "this" can change. How can I delete 4 lines after the last occurrence of the string. I am trying sed -e '/this: /{n;N;N;N;N;d}' but it is deleting after the first occurrence of the string.
Could you please try following.
awk '
FNR==NR{
if($0~/this/){
line=FNR
}
next
}
FNR<=line || FNR>(line+4)
' Input_file Input_file
Output will be as follows with shown samples.
this: name
this: age
Keep everything below here.
You can also use this minor change to make your original sed command work.
sed '/^this:/ { :k ; n ; // b k ; N ; N ; N ; d }' input_file
It uses a loop which prints the current line and reads the next one (n) while it keeps matching the regex (the empty regex // recalls the latest one evaluated, i.e. /^this:/, and the command b k goes back to the label k on a match). Then you can append the next 3 lines and delete the whole pattern space as you did.
Another possibility, more concise, using GNU sed could be this.
sed '/^this:/ b ; /^/,$ { //,+3 d }' input_file
This one prints any line beginning with this: (b without label goes directly to the next line cycle after the default print action).
On the first line not matching this:, two nested ranges are triggered. The outer range is "one-shot". It is triggered right away due to /^/ which matches any line then it stays triggered up to the last line ($). The inner range is a "toggle" range. It is also triggered right away because // recalls /^/ on this line (and only on this line, hence the one-shot outer range) then it stays trigerred for 3 additional lines (the end address +3 is a GNU extension). After that, /^/ is no longer evaluated so the inner range cannot trigger again because // recalls /^this:/ (which is short cut early).
This might work for you (GNU sed):
sed -E ':a;/this/n;//ba;$!N;$!ba;s/^([^\n]*\n?){4}//;/./!d' file
If the pattern space (PS) contains this, print the PS and fetch the next line.
If the following line contains this repeat.
If the current line is not the last line, append the next line and repeat.
Otherwise, remove the first four lines of the PS and print the remainder.
Unless the PS is empty in which case delete the PS entirely.
N.B. This only reads the file once. Also the OP says
How can I delete 4 lines after the last occurrence of the string
However the example would seem to expect 5 lines to be deleted.
vim: insert original line number in g/pattern/move $
I'm debugging some event order in a log and like to check two set of events sequence by the line number of the showing log. Usually, I used g/pattern/move $ for some interesting info. But I cannot find a way to insert the original line number of them. Please help.
I tried :
g/pattern/move $; printf("%d",line("."))
but it does not work.
Can't help thinking of something very straightforward, for example:
g/pattern/call append(line('$'), line('.') . ' ' . getline('.'))
A slightly different way but I have following mapping in my _vimrc
nnoremap <F3> :redir! #f<cr>:silent g//<cr>:redir! END<cr>:enew!<cr>:put! f<cr>:let #f=#/<cr>:g/^$/d<cr>:let #/=#f<cr>gg
It opens a new buffer with all your search matches, including the linenumbers where the match occured.
I have figured out a way to insert at first the line number on the lines that have the pattern and after that moving the same lines to the end of the file:
:%s,\v^\ze.*pattern,\=line('.') . ' ' ,g | g/pattern/m$
We have two commands:
:%s,\v^\ze.*pattern,\=line('.') . ' ' ,g
, ....................... we are using comma as delimiter
\v ...................... very magic substitution
^ ....................... Regular expression for beginning of line
\ze ..................... indicates that all after it will not be substituted
\=line('.') ............. gets the line number
. ' ' .................. concatenates one space after the number
The second command is separated with |
g/pattern/m$
m$ ....................... moves the pattern to the end of file
let i=1 | g/aaa\zs/s//\=i/ | let i=i+1
The above command add counter number after matched pattern. So the following text is changed.
aaab
aaab
aaab
to
aaa1b
aaa2b
aaa3b
'|' joints commands into one command. In my opinion, the commands are executed sequentially like firstly let i=1, then g/aaa\zs/s//\=i/ , finally let i=i+1 . From the result above, s//\=i/**and **let i=i+1 are executed by g command. Can anyone explain?
The following command does wrong work. But I don't know why.
let i=1 | g/aaa\zs/s//\=i | let i=i+1
In s//\=i/, the replacement string is terminated and the | is treated as an argument by global. However, when you remove the trailing /, the replacement string to s consumes the | let i=i+1. From the help doc for sub-replace-special, you can find: "When the substitute string starts with "\=" the remainder is interpreted as an expression." So the expression i | let i=i+1 is evaluated, but the increment is not available outside of that evaluation.
You should understand your first command as:
let i=1 | g/aaa\zs/ ( s//\=i/ | let i=i+1 )
(Parenthesis are only here for explaining, they'd cause syntax error if typed).
i.e. everything after the g/<pattern/ is a single command given as an argument to the global g command.
So indeed: we start with let i=1, then for all lines matching pattern aaa we execute: s//\=i/ | let i=i+1 (substitution, then incrementing i).
Your second command does not work because s does not function the same way as g, and it does need an ending / after the expression to substitute to pattern.
Usually, the | separates two Ex commands, and they are then indeed executed sequentially. But some commands take a | as part of their arguments. :global is one of them (full list at :help :bar). So, the special application of commands over matching lines is applied with both the :s and the :let commands (the latter of which can be shortened as :let i+=1 BTW).
By outside, I want solutions that does not use Vim's scripting hacks but try to reuse certain basic *ix tools. Inside Vim stuff asks for solutions to get the column-increment with inside stuff such as scripting.
1 1
1 2
1 3
1 ---> 4
1 5
1 6
. .
. .
Vim has a script that does column-vise incrementing, VisIncr. It has gathered about 50/50 ups and down, perhaps tasting a bit reinventing-the-wheel. How do you column-increment stuff in Vim without using such script? Then the other question is, how do you column-increment stuff without/outside Vim?
Most elegant, reusable and preferably-small wins the race!
I don't see a need for a script, a simple macro would do
"a yyp^Ayy
then play it, or map to play it.
Of course, there is always the possibility that I misunderstood the question entirely...
The optimal choice of a technique highly depends on the actual circumstances
of the transformation. There are at least two points variations affecting
implementation:
Whether the lines to operate on are the only ones in a file? If not,
is the range of lines defined by context (i.e. it separated by blank
lines, like a paragraph) or is it arbitrary and should be specified by
user?
Are those lines already contain numbers that should be changed or is
it necessary to insert new ones leaving the text on the lines in tact?
Since there is no information to answer these questions, below we will try to
construct a flexible solution.
A general solution is a substitution operating on the beginnings of the lines
in the range specified by the user. Visual mode is probably the simplest way
of selecting an arbitrary range of lines, so we assume here that boundaries of
the range are defined by the visual selection.
:'<,'>s/^\d\+/\=line(".")-line("''")+1/
If it is necessary to number every line in a buffer, the command can be
simplified as follows.
:%s/^\d\+/\=line('.')/
In any case, if the number should be merely inserted at the beginnings of the
lines (without modifying the ones that already exist), one can change the
pattern from ^\d\+ to ^, and optionally add a separator:
:'<,'>s/^\d\+/\=(line(".")-line("''")+1).' '/
or
:%s/^/\=line('.').' '/
respectively.
For a solution based on command-line tools, one can consider using stream
editors like Sed or text extraction and reporting tools like AWK.
To number each of the lines in a file using Sed, run the commands
$ sed = filename | sed 'N;s/\n/ /'
In order to do the same in AWK, use the command
$ awk '{print NR " " $0}' filename
which could be easily modfied to limit numbering to a particular range of lines
satisfying a certain condition. For example, the following command numbers the
lines two through eight.
$ awk '{print (2<=NR && NR<=8 ? ++n " " : "") $0}' filename
Having an interest in how commands similar to those from the script linked in
the question statement are implemented, one can use the following command as
a reference.
vnoremap <leader>i :call EnumVisualBlock()<cr>
function! EnumVisualBlock() range
if visualmode() != "\<c-v>"
return
endif
let [l, r] = [virtcol("'<"), virtcol("'>")]
let [l, r] = [min([l, r]), max([l, r])]
let start = matchstr(getline("'<"), '^\d\+', col("'<")-1)
let off = start - line("'<")
let w = max(map([start, line("'>") + off], 'len("".v:val)'))
exe "'<,'>" 's/\%'.l.'v.*\%<'.(r+1).'v./'.
\ '\=printf("%'.w.'d",line(".")+off).repeat(" ",r-l+1-w)'
endfunction
If you want change 1 1 1 1 ... to 1 2 3 4 .... (Those numbers should be on different lines.)
:let i=1 | g/1/s//\=i/g | let i+=1
If some of 1 1 1 1 ... are in the same line:
:let g:i = 0
:func! Inc()
: let g:i+=1
: return g:i
:endfun
:%s/1/\=Inc()/g
Is there a command to determine length of a longest line in vim? And to append that length at the beginning of the file?
Gnu's wc command has a -L --max-line-length option which prints out the max line length of the file. See the gnu man wc. The freebsd wc also has -L, but not --max-line-length, see freebsd man wc.
How to use these from vim? The command:
:%!wc -L
Will filter the open file through wc -L and make the file's contents the maximum line length.
To retain the file contents and put the maximum line length on the first line do:
:%yank
:%!wc -L
:put
Instead of using wc, Find length of longest line - awk bash describes how to use awk to find the length of the longest line.
Ok, now for a pure Vim solution. I'm somewhat new to scripting, but here goes. What follows is based on the FilterLongestLineLength function from textfilter.
function! PrependLongestLineLength ( )
let maxlength = 0
let linenumber = 1
while linenumber <= line("$")
exe ":".linenumber
let linelength = virtcol("$")
if maxlength < linelength
let maxlength = linelength
endif
let linenumber = linenumber+1
endwhile
exe ':0'
exe 'normal O'
exe 'normal 0C'.maxlength
endfunction
command PrependLongestLineLength call PrependLongestLineLength()
Put this code in a .vim file (or your .vimrc) and :source the file. Then use the new command:
:PrependLongestLineLength
Thanks, figuring this out was fun.
If you work with tabulations expanded, a simple
:0put=max(map(getline(1,'$'), 'len(v:val)'))
is enough.
Otherwise, I guess we will need the following (that you could find as the last example in :h virtcol(), minus the -1):
0put=max(map(range(1, line('$')), "virtcol([v:val, '$'])-1"))
:!wc -L %
rather than
:%!wc -L
To append that length at the beginning of the file:
:0r !wc -L % | cut -d' ' -f1
Here is a simple, hence easily-remembered approach:
select all text: ggVG
substitute each character (.) with "a": :'<,'>s/./a/g
sort, unique: :'<,'>sort u
count the characters in the longest line (if too many characters to easily count, just look at the column position in the Vim status bar)
I applied this to examine Enzyme Commission (EC) numbers, prior to making a PostgreSQL table:
I copied the ec_numbers data to Calc, then took each column in Neovim, replaced each character with "a",
:'<,'>s/./a/g
and then sorted for unique lines
:'<,'>sort u
aaaaaaa
aaaaaaaa
aaaaaaaaa
aaaaaaaaaa
aaaaaaaaaaa
... so the longest EC number entry [x.x.x.x] is 11 char, VARCHAR(11).
Similarly applied to the Accepted Names, we get
aaaaa
aaaaaa
...
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
i.e. the longest name is 147 char: VARCHAR(200) should cover it!
For neovim users:
local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
local width = #(lines[1])
for _, line in ipairs(lines) do
if #line > width then
width = #line
end
end