Sorting words (not lines) in VIM - bash

Question

The built-in VIM :sort command sorts lines of text. I want to sort words in a single line, e.g. transform the line
b a d c e f
to
a b c d e f
Currently I accomplish this by selecting the line and then using :!tr ' ' '\n' | sort | tr '\n' ' ', but I'm sure there's a better, simpler, quicker way. Is there?
Note that I use bash so if there's a shorter and more elegant bash command for doing this it's also fine.
EDIT: My use-case is that I have a line that says SOME_VARIABLE="one two three four etc" and I want the words in that variable to be sorted, i.e. I want to have SOME_VARIABLE="etc four one three two".
The end result should preferably be mappable to a shortcut key as this is something I find myself needing quite often.

Answer 1

In pure vim, you could do this:
call setline('.', join(sort(split(getline('.'), ' ')), " "))
Edit
To do this so that it works over a range that is less than one line is a little more complicated (this allows either sorting multiple lines individually or sorting part of one line, depending on the visual selection):
command! -nargs=0 -range SortWords call SortWords()
" Add a mapping, go to your string, then press vi",s
" vi" selects everything inside the quotation
" ,s calls the sorting algorithm
vmap ,s :SortWords<CR>
" Normal mode one: ,s to select the string and sort it
nmap ,s vi",s
function! SortWords()
" Get the visual mark points
let StartPosition = getpos("'<")
let EndPosition = getpos("'>")
if StartPosition[0] != EndPosition[0]
echoerr "Range spans multiple buffers"
elseif StartPosition[1] != EndPosition[1]
" This is a multiple line range, probably easiest to work line wise
" This could be made a lot more complicated and sort the whole
" lot, but that would require thoughts on how many
" words/characters on each line, so that can be an exercise for
" the reader!
for LineNum in range(StartPosition[1], EndPosition[1])
call setline(LineNum, join(sort(split(getline('.'), ' ')), " "))
endfor
else
" Single line range, sort words
let CurrentLine = getline(StartPosition[1])
" Split the line into the prefix, the selected bit and the suffix
" The start bit
if StartPosition[2] > 1
let StartOfLine = CurrentLine[:StartPosition[2]-2]
else
let StartOfLine = ""
endif
" The end bit
if EndPosition[2] < len(CurrentLine)
let EndOfLine = CurrentLine[EndPosition[2]:]
else
let EndOfLine = ""
endif
" The middle bit
let BitToSort = CurrentLine[StartPosition[2]-1:EndPosition[2]-1]
" Move spaces at the start of the section to variable StartOfLine
while BitToSort[0] == ' '
let BitToSort = BitToSort[1:]
let StartOfLine .= ' '
endwhile
" Move spaces at the end of the section to variable EndOfLine
while BitToSort[len(BitToSort)-1] == ' '
let BitToSort = BitToSort[:len(BitToSort)-2]
let EndOfLine = ' ' . EndOfLine
endwhile
" Sort the middle bit
let Sorted = join(sort(split(BitToSort, ' ')), ' ')
" Reform the line
let NewLine = StartOfLine . Sorted . EndOfLine
" Write it out
call setline(StartPosition[1], NewLine)
endif
endfunction

Answer 2

Using great ideas from your answers, especially Al's answer, I eventually came up with the following:
:vnoremap <F2> d:execute 'normal i' . join(sort(split(getreg('"'))), ' ')<CR>
This maps the F2 button in visual mode to delete the selected text, split, sort and join it and then re-insert it. When the selection spans multiple lines this will sort the words in all of them and output one sorted line, which I can quickly fix using gqq.
I'll be glad to hear suggestions on how this can be further improved.
Many thanks, I've learned a lot :)
EDIT: Changed '<C-R>"' to getreg('"') to handle text with the char ' in it.

Answer 3

Here's the equivalent in pure vimscript:
:call setline('.',join(sort(split(getline('.'),' ')),' '))
It's no shorter or simpler, but if this is something you do often, you can run it across a range of lines:
:%call setline('.',join(sort(split(getline('.'),' ')),' '))
Or make a command
:command -nargs=0 -range SortLine <line1>,<line2>call setline('.',join(sort(split(getline('.'),' ')),' '))
Which you can use with
:SortLine
:'<,'>SortLine
:%SortLine
etc etc

Answer 4

:!perl -ne '$,=" ";print sort split /\s+/'
Not sure if it requires explanation, but if yes:
perl -ne ''
runs whatever is within '' for every line in input - putting the line in default variable $_.
$,=" ";
Sets list output separator to space. For example:
=> perl -e 'print 1,2,3'
123
=> perl -e '$,=" ";print 1,2,3'
1 2 3
=> perl -e '$,=", ";print 1,2,3'
1, 2, 3
Pretty simple.
print sort split /\s+/
Is shortened version of:
print( sort( split( /\s+/, $_ ) ) )
($_ at the end is default variable).
split - splits $_ to array using given regexp, sort sorts given list, print - prints it.

Answer 5

Maybe you prefer Python:
!python -c "import sys; print(' '.join(sorted(sys.stdin.read().split())))"
Visual select text, and execute this line.

Answer 6

My AdvancedSorters plugin now has a :SortWORDs command that does this (among other sorting-related commands).