How I can assign value by group in Data Step?

[newboy1218]

Hi, I have a dataset like this:

obs  X

1      a

2

3

4      b

5

6

7

8      c

9

10

and I want to end up having this:

obs  X

1      a

2      a

3      a

4      b

5      b

6      b

7      b

8      c

9      c

10     c

How can I do this? I tried to loop through each row but it does not work.

[novinosrin · Accepted solution]

data have;
infile cards truncover;
input obs  X $;
cards;
1      a
2
3
4      b
5
6
7
8      c
9
10
;

data want;
set have;
retain t;
if not missing(x) then t=x;
else x=t;
drop t;
run;