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how to map to the previous variable value??

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Occasional Contributor
Posts: 15

how to map to the previous variable value??

can anyone answer this query??

there is a input variable called X. need to derive variable called 'Y'.. the scenario is wherever there is 999 value there it has to add 0.1 to the previous x value.. if more than one 999 is there then the order should be 3.1, 3.2,3.3

 

X        Y

1        1
2        2
3        3
4        4
999    4.1
1        1
2        2
3        3
999    3.1
999    3.2

SAAAS
Super User
Posts: 19,855

Re: how to map to the previous variable value??

Use the lag function. 

 

X_lag = lag(X);
Y=ifn(X=999, x_lag+0.1, X);

This doesn't deal with consecutive 999 so you'll need to figure out the logic for that.  

Super User
Posts: 10,044

Re: how to map to the previous variable value??

data have;
input X ;
cards; 
1      
2      
3   
4  
999  
1   
2  
3    
999 
999   
;
run;

data want;
 set have;
 retain Y;
 if X ne 999 then Y=X;
  else Y=Y+0.1;
run;
Super User
Posts: 10,044

Re: how to map to the previous variable value??

Or more simple :

 

 

data want;
 set have;
 if X ne 999 then Y=X;
  else Y+0.1;
run;
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