retain statement

[new510]

Hi, 

I have a question regarding retain statement. I have the following dataset:

Dataset:

ID   flag  var1     

A    1       x1         

A    0      x2           

B    0       x1          

B    0       x2         

Result expecting :

ID   flag  var1      want_var2

A    1       x1          x1

A    0      x2           x1

B    0       x1          x1

B    0       x2         x2

 I am trying to retain the value of 'var1' if the flag=1 to the next observation of the same id, and keep the same value of var1 if the flag=0.

I am using the  code as below:

data xy;

input id $ flag $ z $;

datalines;

A 1 A1

A 0 A2

B 0 B1

B 0 B2

;

run;

proc sort data=xy; by id descending flag; run;

data xyz;

set xy;

by id descending flag;

retain xy xy2;

if first.id and flag=1 then do;

xy=Z;

end;

else if first.id and flag=0 then do;

xy=z;

end;

run;

Thank you in advance. 

[ChrisNZ · Accepted solution]

I think you misunderstand what RETAIN does.

This does what you want:

data WANT; 
  set HAVE;
  LAST_VAR1=lag(VAR1);
  VAR2=ifc(lag(FLAG)=1 & lag(ID)=ID, LAST_VAR1, VAR1);
  drop LAST_VAR1; 
run;

ID	FLAG	VAR1	VAR2
A	1	x1	x1
A	0	x2	x1
B	0	x1	x1
B	0	x2	x2

[new510]

Thank you, ChrisNZ

[novinosrin]

data xy;

input id $ flag  var1 $;

datalines;
A    1       x1         
A    0      x2           
B    0       x1          
B    0       x2  
;

run;

data want;
set xy;
by id;
retain want;
if first.id then _flag=0;
_flag+flag;
if flag or _flag=0 then want=var1 ;
drop _:;
run;