Dear All:
My Data is as follows
ID Date VarA
1 01JAN2018 0
1 03JAN2018 0
1 21JAN2018 1
1 03FEB2018 1
1 20FEB2018 1
1 03MAR2018 0
1 15MAR2018 1
1 05APR2018 0
2 20JAN208 1
2 29JAN2018 0
2 05FEB2018 0
2 18FEB2018 1
2 22FEB2018 0
2 25FEB2018 0
I want to create a variable which tracks changes from 1 to 0 for VarA for each ID. So the data set I want is
ID Date VarA VarB
1 01JAN2018 0 0
1 03JAN2018 0 0
1 21JAN2018 1 0
1 03FEB2018 1 0
1 20FEB2018 1 0
1 03MAR2018 0 1
1 15MAR2018 1 0
1 05APR2018 0 2
2 20JAN208 1 0
2 29JAN2018 0 1
2 05FEB2018 0 1
2 18FEB2018 1 0
2 22FEB2018 0 2
2 25FEB2018 0 2
So the change occurs from 1 to 0 and I want to keep a track of the number of such changes.
Thanks so much.
Randy
data have;
input ID Date : $20. VarA ;
cards;
1 01JAN2018 0
1 03JAN2018 0
1 21JAN2018 1
1 03FEB2018 1
1 20FEB2018 1
1 03MAR2018 0
1 15MAR2018 1
1 05APR2018 0
2 20JAN208 1
2 29JAN2018 0
2 05FEB2018 0
2 18FEB2018 1
2 22FEB2018 0
2 25FEB2018 0
;
data want;
set have;
varb=0;
if id ne lag(id) then count=0;
if id eq lag(id) and vara=0 and lag(vara)=1 then count+1;
if vara=0 then varb=count;
drop count;
run;
The last value of varb is inconsistent, there is no change in vara for that observation.
Assuming the last value of varb in your example should be zero :
data want;
count = 0;
do until(last.id);
set have; by id vara notsorted;
if first.vara and vara = 0 then do;
count + 1;
varb = count;
end;
else varb = 0;
output;
end;
drop count;
run;
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