How to sum across

[Sizzen]

How i need to sum first column with another column across?

i mean this:

data stock;
input Astock  Bstock;
cards;
500 250
200 658
300 425
400 125
;
run;

data sum;
set stock;
sum=sum(Astock,Bstock);
run;

How i need to change it ?

[PeterClemmensen · Accepted solution]

Like this?

data stock;
input Astock  Bstock;
cards;
500 250
200 658
300 425
400 125
;
run;

data want;
   set stock;

   lag_Astock = lag1(Astock);
   if not missing(lag_Astock) then total = sum(Bstock,lag_Astock);

   drop lag_Astock;
run;

[Sizzen]

Thanks !!

[Sizzen]

One more question :

If i have 

And i need to find average of three variables and write to next, but first meaning is missing, so i don't need that;;

data numbers;
input A;
cards;
500
400
300
200
800
200
;
run;

data mean;
set numbers;
first = lag(A);
second=lag2(A);
third=lag3(A);
if _n_ ge 3 then mean= mean(of first,second,third);
final=lag1(mean);
run;

but first of all it find mean of    missing value+500+400/3=300

How to change ?

[ballardw]

If you want a value to be counted in the denominator (3) then there must be a value in the numerator. which would have to be 0 if I understand what you are attempting if you want to use the MEAN function.

Or

mean = sum(of first,second,third) / 3;

When you start getting to complicated requirements to use values that are not in your data then you will have to provide the values using your business logic.