I have a dataset that has multiple groups of observations. There is a variable, flag, which either takes value 1 or missing. I want to create a new variable to divide each group into subgroups based on the value of flag. Whenever flag = 1, start counting a new subgroup. Please see the code below as an example.
data have;
input group flag;
datalines;
101 .
101 .
101 1
101 .
101 1
101 .
101 .
102 .
102 1
102 .
102 .
;
data want;
input group flag new_var;
datalines;
101 . 1
101 . 1
101 1 2
101 . 2
101 1 3
101 . 3
101 . 3
102 . 1
102 1 2
102 . 2
102 . 2
;
data want;
set have;
by group;
if first.group
then newvar = 1;
else if flag then newvar + 1;
run;
please try the below code for flag2
data have;
input group flag;
datalines;
101 .
101 .
101 1
101 .
101 1
101 .
101 .
102 .
102 1
102 .
102 .
;
data want;
set have;
by group flag notsorted;
retain new_var;
if first.group then new_var=1;
else new_var+flag;
run;
data want;
set have;
by group;
if first.group
then newvar = 1;
else if flag then newvar + 1;
run;
If you want a more arcane solution, try:
data want;
set have;
by group;
length new_var 8;
retain new_var;
new_var = ifn(first.group, 1, new_var) + sum(0, flag);
run;
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