Identify unpaired data

[rstuart931]

I have a dataset where the same sample ID is associated with two components (a and b), it also contains singular data (c). I'm trying to add a column that counts the number of occurrences of the ID so I can identify when I only have one of the two components. I'm trying to create the Count column in the table below so I could identify the unpaired component (in red text) using an if then statement (if Comp eq "a" and Count ne 2 then) and (if Comp eq "b" and Count ne 2 then).

Comp	ID	Count
c	5236	1
a	3298	2
b	3298	2
a	4172	1
a	8723	2
b	8723	2
c	7692	1

If it were in Excel, it could be done using the COUNTIF function and dragging it down (=COUNTIF(B:B,B2)) Unfortunately I don't even know where to begin to do this in SAS and haven't had any luck Googling it. I would appreciate any direction you could give me.

[PaigeMiller · Accepted solution]

In my mind, counting questions are best handled by PROC FREQ.

proc freq data=have;
     tables id/noprint out=counts;
run;

data want;
    merge have counts(keep=id count);
    by id;
run;

You have to sort data set HAVE by ID in order for this to work.

[rstuart931]

@PaigeMiller Thank you, that worked great!