count and group the column by sequence - sas

Question

I have a dataset that has to be grouped by number as follows.
ID dept count
1 10 2
2 10 2
3 20 4
4 20 4
5 20 4
6 20 4
7 30 4
8 30 4
9 30 4
10 30 4
so for every 3rd row I need a new level the output should be as follows.
ID dept count Level
1 10 2 1
2 10 2 1
3 20 4 1
4 20 4 1
5 20 4 2
6 20 4 2
7 30 4 1
8 30 4 1
9 30 4 2
10 30 4 2
I have tried counting the number of rows based on the dept and count.
data want;
set have;
by dept count;
if first.count then level=1;
else level+1;
run;
this generates a count but not what exactly I am looking for
ID dept count Level
1 10 2 1
2 10 2 1
3 20 4 1
4 20 4 1
5 20 4 2
6 20 4 2
7 30 4 1
8 30 4 1
9 30 4 2
10 30 4 2

Answer 1

It isn't quite clear what output you want. I've extended your input data a bit - please
could you clarify what output you'd expect for this input and what the logic is for generating it?
I've made a best guess at roughly what you might be aiming for - incrementing every 3 rows with the same dept and count - perhaps this will be enough for you to get to the answer you want?
data have;
input ID dept count;
cards;
1 10 2
2 10 2
3 20 4
4 20 4
5 20 4
6 20 4
7 30 4
8 30 4
9 30 4
10 30 4
11 30 4
12 30 4
13 30 4
14 30 4
;
run;
data want;
set have;
by dept count;
if first.count then do;
level = 0;
dummy = 0;
end;
if mod(dummy,3) = 0 then level + 1;
dummy + 1;
drop dummy;
run;
Output:
ID dept count level
1 10 2 1
2 10 2 1
3 20 4 1
4 20 4 1
5 20 4 1
6 20 4 2
7 30 4 1
8 30 4 1
9 30 4 1
10 30 4 2
11 30 4 2
12 30 4 2
13 30 4 3
14 30 4 3

Answer 2

One way to do this is to nest the SET statement inside a DO loop. Or in this case two DO loops. One to generate the LEVEL (within DEPT) and the second to count by twos. Use the LAST.DEPT flag to handle odd number of observations.
So if I modify the input to include odd number of observations in some groups.
data have;
input ID dept count;
cards;
1 10 2
2 10 2
3 20 4
4 20 4
5 20 4
6 20 4
7 20 4
8 30 4
9 30 4
10 30 4
;
Then can use this step to assign the LEVEL variable.
data want ;
do level=1 by 1 until(last.dept);
do sublevel=1 to 2 until(last.dept);
set have;
by dept;
output;
end;
end;
run;
Results:
Obs level sublevel ID dept count
1 1 1 1 10 2
2 1 2 2 10 2
3 1 1 3 20 4
4 1 2 4 20 4
5 2 1 5 20 4
6 2 2 6 20 4
7 3 1 7 20 4
8 1 1 8 30 4
9 1 2 9 30 4
10 2 1 10 30 4