Assign Group ID for Same Values in Increasing Order

[wentao]

I would like to assign group id for same values,

like showed below, if I have code_name, how to get group id number?

code_name    group_id_number

aa                     1

aa                     1

aa                     1

bb                    2

cc                     3

cc                     3

dd                    4

ee                    5

ff                      6

gg                    7

gg                    7

.                               .

.                               .

.                               .

[LinusH]

Use a data step with BY processing.
Then
if first.codename then group_id_number+1;
You need to initialize group_id_number to 0 (hint: _n_=0)

[wentao]

Here is my code:

data test;
set test2 (keep = codename);
by code_name;

s_id = _n_ = 0;

if first.codename then s_id + 1;
run;

proc print data = test (obs = 100);
var codename s_id;
run;

And the out are something like this:

It only assign "1" to the very first codename and the duplicates will just have 0 assigned

aa                     1

aa                     0

aa                     0

bb                    1

cc                     1

cc                     0

dd                    1

ee                    1

ff                      1

gg                    1

gg                    0

.                               .

.                               .

.                               .

[Kurt_Bremser · Accepted solution]

Although a retain statement is not needed when you use the s_id + 1 syntax, I like to use it for initializing:

data test;
set test2 (keep = codename);
by codename;
retain s_id 0;
if first.codename then s_id + 1;
run;

Edit: fixed a typo in the by statement (wrong underline)

[wentao]

Thanks!!

It worked perfectly!