Comparing consecutive rows within an file - unix

Question

I have two files with with 1s and 0s in each column, where the field separator is "," :
1,0,0,1,1,1,0,0,0,0,1,0,0,1,1,0,1,0
0,1,0,1,1,1,0,1,0,1,0,0,0,0,0,0,0,0
1,0,0,0,1,0,0,1,0,0,0,1,0,0,1,0,1,0
1,0,0,0,1,0,0,1,0,0,0,1,0,0,1,0,1,0
1,0,1,0,0,0,0,1,1,1,1,1,1,1,1,1,0,1
1,0,1,0,0,0,0,1,1,1,1,1,1,1,1,1,0,0
1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0
1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0
1,1,1,0,0,0,1,1,1,0,0,0,1,1,1,0,0,0
1,1,1,0,0,0,1,1,1,0,0,0,1,1,1,0,0,0
Want I want to do is look at the file in pairs of rows, compare them, and if they are exactly the same output a 1. So for this example the rows 1 & 2 are different so they don't get a 1, rows 3 & 4 are exactly the same so they get a 1, and rows 5&6 differ by 1 column so they don't get a 1, and so on.
So the desired output could be something like :
1
1
1
Because here there are exactly 3 pairs (they are paired by the fact if they are consecutive) of rows that are exactly the same: rows 3&4, 7&8, and 9&10. The comparison should not reuse a row, so if you compare rows 1 & 2, you shouldn't then compare rows 2 & 3.

Answer 1

You can do this with awk like:
awk -F, '!(NR%2) {print $0==p} {p=$0}' data
0
1
0
1
1
where every line that's evenly divisible by two will print a 0 if the current line doesn't match the last value for p or a 1 if it matches.
If you truly only want the 1s, which is throwing away any information about which pairs matched, you could:
awk -F, '!(NR%2)&&$0==p {print 1} {p=$0}' data
1
1
1
Alternatively, you could output matching pair line numbers like:
awk -F, '!(NR%2)&&$0==p {print NR-1 "," NR} {p=$0}' data
3,4
7,8
9,10
Or just the counts of all matched pairs:
awk -F, '!(NR%2)&&$0==p {c++} {p=$0} END{ print c}' data
3
Another useful variant might be just to return the matching lines directly:
awk -F, '!(NR%2)&&$0==p {print} {p=$0}' data
1,0,0,0,1,0,0,1,0,0,0,1,0,0,1,0,1,0
1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0
1,1,1,0,0,0,1,1,1,0,0,0,1,1,1,0,0,0

Answer 2

I would use a shell script like this:
while read line
do
if test "$prevline" = "$line"
then
echo 1
fi
prevline=$line
done
I'm not 100% sure about your requirement to "not reuse a row", but I think that could be achieved by changing inner part of the loop to
if test "$prevline" = "$line"
then
echo 1
line="" # don't reuse a line
fi