how to calculate sum and replace it in missing value

[mj5]

I have a dataset as below

PT     N

102   25

103   34

Total   .

I need to replace the missing with the sum of the 2 counts in N. Can i do that in datastep?

[Kurt_Bremser · Accepted solution]

You can retain a variable where you sum up all N values, and when PT = 'Total', you set N to that value.

[RW9]

Whilst @Kurt_Bremser has given you the answer, I would step back one and ask why you have a dataset which looks like that in the first place.  How have you added "Total" without adding the sum in at the same time, seems like the step before needs changing.  You can add totals on in various ways, my first thought was:

proc sql;
  create table WANT as
  select  *
  from    HAVE
  union all
  select  "Total",
          sum(N) 
  from    HAVE;
quit;

Simply adds a row at the end of the dataset with total.