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

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

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 4

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 5

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 6

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 7

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 8

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 9

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

Answer 10

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 11

$ 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 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!