CODEWITHSUNDEEP
if-statementsas
Laura
Laura

Reputation: 45

Multiple conditions for same variable in SAS

I'm trying to detect specific values of one variable and create a new one if those conditions are fulfilled.

Here's a part of my data (I have much more rows) :

id time result 
1  1    normal 
1  2    normal 
1  3    abnormal 
2  1    normal 
2  2    
3  3    normal  
4  1    normal 
4  2    normal      
4  3    abnormal  
5  1    normal 
5  2    normal   
5  3

What I want 

id time result    base 
1  1    normal 
1  2    normal      x
1  3    abnormal 
2  1    normal      x
2  2  
2  3    normal  
3  3    normal          
4  1    normal 
4  2    normal      x
4  3    abnormal    
5  1    normal 
5  2    normal      x
5  3

My baseline value (base) should be populated when result exists at timepoint (time) 2. If there's no result then baseline should be at time=1. 

if result="" and time=2 then do; 
if time=10 and result ne "" then base=X; end;

if result ne "" and time=2 then base=X;  `

It works correctly when time=2 and results exists. But if results missing, then there's something wrong.

Upvotes: 0

Views: 2279

Answers (1)

pinegulf
pinegulf

Reputation: 1396

The question seems a bit off. "Else if time="" and time=1" There seems to be a typo there somewhere.

However, your syntax seems solid. I've worked an example with your given data. The first condition works, but second (else if ) is assumption. Updating as question is updated.

options missing='';
    data begin;
    input id time  result $ 5-20 ;
    datalines;
    1  1    normal 
    1  2    normal 
    1  3    abnormal 
    2  1    normal 
    2  2         
    3  3    normal  
    4  1    normal 
    4  2    normal      
    4  3    abnormal 
    ;
run;

data flagged;
    set begin;
    if time=2 and result NE "" then base='X';
    else if time=1 and id=2 then base='X';
run;

Edit based on revisited question.

Assuming that the time-point (1) is always next to the point (2). (If not, then add more lags.) Simulating the Lead function we sort the data backwards and utilize lag. 

proc sort data=begin; by id descending time; run;

data flagged;
    set begin;
    if lag(time)=2 and lag(result) EQ "" then base='X'; 
    if time=2 and result NE "" then base='X';
run;

More about opposite of lag: https://communities.sas.com/t5/SAS-Communities-Library/How-to-simulate-the-LEAD-function-opposite-of-LAG/ta-p/232151

Upvotes: 2

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