In SAS --Summing binary is producing Binary Results - sas

Question

I am trying to convert a categorical variable (Product) in binary and then want to know how many products per customer.
data is in the following format:
ID Product
C1 A
C1 B
C2 A
C3 B
C4 A
The code I am using for converting category to binary
IF PRODUCT="A" THEN PROD_A =1 ; ELSE PROD_A=0;
IF PRODUCT="B" THEN PROD_B =1 ; ELSE PROD_B=0;
TOT_PROD = SUM(PROD_A, PROD_B);
But when I count no. of product it gives me '1' for all customer and I am expecting 1 or 2.
I have tried
TOT_PROD = PROD_A + PROD_B;
but I get the same results

Answer 1

This is all inside one datastep, correct? If so you're processing only one line at a time. For each individual line the only possible values for PROD_A and PROD_B are one or zero. You need an aggregate function. For example, if your dataset is named PRODUCTS:
DATA X;
SET PRODUCTS;
IF PRODUCT="A" THEN PROD_A = 1 ; ELSE PROD_A=0;
IF PRODUCT="B" THEN PROD_B = 1 ; ELSE PROD_B=0;
TOT_PROD = SUM(PROD_A, PROD_B);
RUN;
(TOT_PROD will always be equal to 1 in X, but never mind for now).
Now sum them up:
proc sql;
create table prod_totals as
select product, sum(tot_prod) as total_products
from x
group by product;
quit;
More simply just skip the data step:
proc sql;
create table prod_totals as
select product, count(*) as total_products
from products
group by product;
quit;
Or use PROC SUMMARIZE or PROC MEANS instead of PROC SQL.

Answer 2

I have assumed you only want 1 record output per id.
In the solutions below I have employed the DOW-Loop (DO-Whitlock).
If you wanted prod_a and prod_b just to help with the totals and if they're not required in the output, then you could use something like:
data want;
do until(last.id);
set have;
by id;
tot_prod=sum(tot_prod,product='A',product='B');
end;
run;
If you need prod_a and prod_b in the output, then you could use:
data want;
do until(last.id);
set have;
by id;
prod_a=(product='A');
prod_b=(product='B');
tot_prod=sum(tot_prod,prod_a,prod_b);
end;
run;
In both data steps the last product per id will be output along with the other variables and in the case of the 2nd data step example the last prod_a & prod_b per id will also be output.

Answer 3

To do this in the data step, you need retain. Make sure you've sorted the dataset by id first.
data prod_totals;
set products;
by ID;
retain prod_a prod_b;
if first.id then do; *initialize to zero for each new ID;
prod_a=0; prod_b=0;
end;
if product='A' then prod_a=1; *set to 1 for each one found;
else if product='B' then prod_b=1;
if last.id then do; *for last record in each ID, output and sum total;
total_products=sum(prod_a,prod_b);
output;
end;
keep id prod_a prod_b total_products;
run;