re: change entries based on conditions

[twildone]

Hi....I am trying to correct the entries in Dept for the same ID by changing them to the entry that is entered for Dept when Section = s1 except for when Dept=a4. Any suggestions? Thanks

data one;
input ID Dept$ Section$ credit;
datalines;
1 a1 s1    
1 a1 s2 0.5
1 a2 s3 1.0
1 a2 s4 1.0
1 a4 s5 1.0
1 a4 s6      
2 a1 s3 1.0
2 a1 s2 0.5
2 a2 s1    
2 a3 s4 1.0
2 a4 s5 1.0
2 a1 s5 0.5
2 a1 s5 1.0
2 a1 s6 1.0
2 a3 s6    
2 a2 s6 1.0
3 a4 s5 0.5
3 a2 s5    
3 a2 s5 1.0
3 a1 s1    
3 a1 s2 1.0
3 a1 s3 1.0
;
run;

 Want:

data want;

1 a1 s1    

1 a1 s2 0.5

1 a1 s3 1.0

1 a1 s4 1.0

1 a4 s5 1.0

1 a4 s6     

2 a2 s3 1.0

2 a2 s2 0.5

2 a2 s1  

2 a2 s4 1.0

2 a4 s5 1.0

2 a2 s5 0.5

2 a2 s5 1.0

2 a2 s6 1.0

2 a2 s6  

2 a2 s6 1.0

3 a4 s5 0.5

3 a1 s5    

3 a1 s5 1.0

3 a1 s1  

3 a1 s2 1.0

3 a1 s3 1.0

[ChrisNZ · Accepted solution]

One way:

data WANT; 
  merge ONE ONE(keep=ID DEPT SECTION rename=(DEPT=D SECTION=S) where=(S='s1'));
  by ID;
  if DEPT ne 'a4' then DEPT=D;
  drop D S;
run;

 [Edited to add a4 exception]