add an column

[sasphd]

hello,

I want to add a column of obs which count the number of observations by id

table

id     a    

1     2    

1     6    

1     5    

2     4    

2     9    

2     4    

2     5    

I want to have

id     a     obs

1     2     1

1     6     2

1     5     3

2     4     1

2     9     2

2     4     3

2     5     4

[stat_sas · Accepted solution]

data want;

set have;

by id;

if first.id then obs=0;

obs+1;

run;