Reorder lines of file by given sequence - bash

Question

I have a document A which contains n lines. I also have a sequence of n integers all of which are unique and <n. My goal is to create a document B which has the same contents as A, but with reordered lines, based on the given sequence.
Example:
A:
Foo
Bar
Bat
sequence: 2,0,1 (meaning: First line 2, then line 0, then line 1)
Output (B):
Bat
Foo
Bar
Thanks in advance for the help

Answer 1

Another solution:
You can create a sequence file by doing (assuming sequence is comma delimited):
echo $sequence | sed s/,/\\n/g > seq.txt
Then, just do:
paste seq.txt A.txt | sort tmp2.txt | sed "s/^[0-9]*\s//"
Here's a bash function. The order can be delimited by anything.
Usage: schwartzianTransform "A.txt" 2 0 1
function schwartzianTransform {
local file="$1"
shift
local sequence="$#"
echo -n "$sequence" | sed 's/[^[:digit:]][^[:digit:]]*/\
/g' | paste -d ' ' - "$file" | sort -n | sed 's/^[[:digit:]]* //'
}

Answer 2

Read the file into an array and then use the power of indexing :
echo "Enter the input file name"
read ip
index=0
while read line ; do
NAME[$index]="$line"
index=$(($index+1))
done < $ip
echo "Enter the file having order"
read od
while read line ; do
echo "${NAME[$line]}";
done < $od
[aman#aman sh]$ cat test
Foo
Bar
Bat
[aman#aman sh]$ cat od
2
0
1
[aman#aman sh]$ ./order.sh
Enter the input file name
test
Enter the file having order
od
Bat
Foo
Bar

Answer 3

an awk oneliner could do the job:
awk -vs="$s" '{d[NR-1]=$0}END{split(s,a,",");for(i=1;i<=length(a);i++)print d[a[i]]}' file
$s is your sequence.
take a look this example:
kent$ seq 10 >file #get a 10 lines file
kent$ s=$(seq 0 9 |shuf|tr '\n' ','|sed 's/,$//') # get a random sequence by shuf
kent$ echo $s #check the sequence in var $s
7,9,1,0,5,4,3,8,6,2
kent$ awk -vs="$s" '{d[NR-1]=$0}END{split(s,a,",");for(i=1;i<=length(a);i++)print d[a[i]]}' file
8
10
2
1
6
5
4
9
7
3

Answer 4

One way(not an efficient one though for big files):
$ seq="2 0 1"
$ for i in $seq
> do
> awk -v l="$i" 'NR==l+1' file
> done
Bat
Foo
Bar
If your file is a big one, you can use this one:
$ seq='2,0,1'
$ x=$(echo $seq | awk '{printf "%dp;", $0+1;print $0+1> "tn.txt"}' RS=,)
$ sed -n "$x" file | awk 'NR==FNR{a[++i]=$0;next}{print a[$0]}' - tn.txt
The 2nd line prepares a sed command print instruction, which is then used in the 3rd line with the sed command. This prints only the line numbers present in the sequence, but not in the order of the sequence. The awk command is used to order the sed result depending on the sequence.