Counting with conditions

[tonoplast]

Dear SAS community,

I am having trouble counting and resetting the count with conditions and your help would be much appreciated.

Suppose that I have data below;

Subject / Year / Condition

A 1991 2

A 1992 2

A 1993 1

A 1994 2

A 1995 2

B 1990 1

B 1991 2

B 1992 1

B 1993 2

C 1991 2

C 1992 2

C 1993 2

C 1994 2

C 1995 1

I cannot change the order of this, and I would like to start counting

when first "1" appears and continue counting through "2" and reset each time "1" appears for the same individual.

so that it would give me:

A 1991 2 0

A 1992 2 0

A 1993 1 1

A 1994 2 2

A 1995 2 3

B 1990 1 1

B 1991 2 2

B 1992 1 1

B 1993 2 2

C 1991 2 0

C 1992 2 0

C 1993 2 0

C 1994 2 0

C 1995 1 1

How can I achieve this? Please help. Thank you!

Regards,

T

[Astounding · Accepted solution]

Here's one way:

data want;
set have;
by subject;
if first.subject then newvar=0;
if condition = 1 then newvar = 1;
else if condition = 2 then do;
   if newvar then newvar + 1;
end;
run;

The  condition "if newvar" will be false when NEWVAR is 0, true when it is some other integer.

[tonoplast]

Thank you!! This works perfectly!

[novinosrin]

data have;
input Subject $ Year  Condition	;
cards;
A 1991 2
A 1992 2
A 1993 1
A 1994 2
A 1995 2
B 1990 1
B 1991 2
B 1992 1
B 1993 2
C 1991 2
C 1992 2
C 1993 2
C 1994 2
C 1995 1
;

data want;
set have;
by subject;
if first.subject then want=0;
if condition=1 then want=1;
else if want then want+1;
run;

[tonoplast]

And this too! Thank you very much!