How do I split up a line and rearrange its elements?

Question

I have some data on a single line like below

abc edf xyz rfg yeg udh

I want to present the data as below

abc
xyz
yeg


edf
rfg
udh

so that alternate fields are printed with newline separated. Are there any one liners for this?

Answer 1

The following awk script can do it:

> echo 'abc edf xyz rfg yeg udh' | awk '{
    for (i = 1;i<=NF;i+=2){print $i}
    print "";
    for (i = 2;i<=NF;i+=2){print $i}
    }'
abc
xyz
yeg

edf
rfg
udh

Answer 2

Python in the same spirit as the above awk (4 lines):

$ echo 'abc edf xyz rfg yeg udh' | python -c 'f=raw_input().split()
> for x in f[::2]: print x
> print
> for x in f[1::2]: print x'

Python 1-liner (omitting the pipe to it which is identical):

$ python -c 'f=raw_input().split(); print "\n".join(f[::2] + [""] + f[1::2])'

Answer 3

Just for comparison, here's a few Perl scripts to do it (TMTOWTDI, after all). A rather functional style:

#!/usr/bin/perl -p

use strict;
use warnings;

my @a = split;
my @i = map { $_ * 2 } 0 .. $#a / 2;
print join("\n", @a[@i]), "\n\n",
      join("\n", @a[map { $_ + 1 } @i]), "\n";

We could also do it closer to the AWK script:

#!/usr/bin/perl -p

use strict;
use warnings;

my @a = split;
my @i = map { $_ * 2 } 0 .. $#a / 2;
print "$a[$_]\n" for @i;
print "\n";
print "$a[$_+1]\n" for @i;

I've run out of ways to do it, so if any other clever Perlers come up with another method, feel free to add it.

Answer 4

you could also just use tr: echo "abc edf xyz rfg yeg udh" | tr ' ' '\n'

Answer 5

Another Perl solution:

use strict;
use warnings;

while (<>)
{
    my @a = split;
    my @b = map { $a[2 * ($_%(@a/2)) + int($_ / (@a /2))]  . "\n" } (0 .. @a-1); 
    print join("\n", @a[0..((@b/2)-1)], '', @a[(@b/2)..@b-1], '');
}

You could even condense it into a real one-liner:

perl -nwle'my @a = split;my @b = map { $a[2 * ($_%(@a/2)) + int($_ / (@a /2))]  . "\n" } (0 .. @a-1);print join("\n", @a[0..((@b/2)-1)], "", @a[(@b/2)..@b-1], "");'

Answer 6

Here's the too-literal, non-scalable, ultra-short awk version:

awk '{printf "%s\n%s\n%s\n\n%s\n%s\n%s\n",$1,$3,$5,$2,$4,$6}'

Slightly longer (two more characters), using nested loops (prints an extra newline at the end):

awk '{for(i=1;i<=2;i++){for(j=i;j<=NF;j+=2)print $j;print ""}}'

Doesn't print an extra newline:

awk '{for(i=1;i<=2;i++){for(j=i;j<=NF;j+=2)print $j;if(i==1)print ""}}'

For comparison, paxdiablo's version with all unnecessary characters removed (1, 9 or 11 more characters):

awk '{for(i=1;i<=NF;i+=2)print $i;print "";for(i=2;i<=NF;i+=2)print $i}'

Here's an all-Bash version:

d=(abc edf xyz rfg yeg udh)
i="0 2 4 1 3 5"
for w in $i
do
    echo ${d[$w]}
    [[ $w == 4 ]]&&echo
done

Answer 7

Another Perl 5 version:

#!/usr/bin/env perl
use Modern::Perl;
use List::MoreUtils qw(part);

my $line = 'abc edf xyz rfg yeg udh';

my @fields = split /\s+/, $line; # split on whitespace

# Divide into odd and even-indexed elements
my $i = 0;
my ($first, $second) = part { $i++ % 2 }  @fields;

# print them out
say for @$first;
say '';          # Newline
say for @$second;

Answer 8

Ruby versions for comparison:

ARGF.each do |line|
  groups = line.split
  0.step(groups.length-1, 2) { |x| puts groups[x] }
  puts
  1.step(groups.length-1, 2) { |x| puts groups[x] }
end

ARGF.each do |line|
  groups = line.split
  puts groups.select { |x| groups.index(x) % 2 == 0 }
  puts
  puts groups.select { |x| groups.index(x) % 2 != 0 }
end

Answer 9

A shame that the previous perl answers are so long. Here are two perl one-liners:

echo 'abc edf xyz rfg yeg udh'|
  perl -naE '++$i%2 and say for @F; ++$j%2 and say for "",@F'

On older versions of perl (without "say"), you may use this:

echo 'abc edf xyz rfg yeg udh'|
  perl -nae 'push @{$a[++$i%2]},"$_\n" for "",@F; print map{@$_}@a;'

Answer 10

$ echo 'abc edf xyz rfg yeg udh' |awk -vRS=" " 'NR%2;NR%2==0{_[++d]=$0}END{for(i=1;i<=d;i++)print _[i]}'
abc
xyz
yeg
edf
rfg
udh

For newlines, i leave it to you to do yourself.

Answer 11

My attempt in haskell:

Prelude> (\(x,y) -> putStr $ unlines $ map snd (x ++ [(True, "")] ++ y)) $ List.partition fst $ zip (cycle [True, False]) (words "abc edf xyz rfg yeg udh")
abc
xyz
yeg

edf
rfg
udh
Prelude>

Answer 12

Here is yet another way, using Bash, to manually rearrange words in a line - with previous conversion to an array:

echo 'abc edf xyz rfg yeg udh' | while read tline; do twrds=($(echo $tline)); echo -e "${twrd[0]} \n${twrd[2]} \n${twrd[4]} \n\n ${twrd[1]} \n${twrd[3]} \n${twrd[5]} \n" ; done 

Cheers!