Do loops not sure if I am using the right step

[Syndey]

Hi I have the following data below. For each customer I want to take the top four ranks but within these four obs there must only be one observation that has flag_2=1 and flag__1=0. I have highlighted in red the records I would want selected. I'm struggling to work out how I can do this. thanks

Cust	Rank	Flag_1	Flag_2
A	1	1	0
A	2	1	1
A	3	1	1
A	4	0	1
A	5	0	1
A	6	1	0
A	7	0	0
B	1	1	0
B	2	1	0
B	3	0	0

[billfish]

A solution amongst others:

data have;
input Cust $ Rank Flag_1 Flag_2;
cards;
A 1 1 0
A 2 1 1
A 3 1 1
A 4 0 1
A 5 0 1
A 6 1 0
A 7 0 0
B 1 1 0
B 2 1 0
B 3 0 0
;
run;

proc sort data=have; by cust descending rank; run;

data want(keep=cust rank flag_1 flag_2);
   set have;
   by cust;

   retain zSum zOne;

   if first.cust then do; zSum=0; zOne=0; end;
   if (zSum <4) and not((flag_1=0) and (flag_2=1)) then do;
       zSum+1;
       output;
   end;
   if (zOne=0) and (zSum<4) and ((flag_1=0) and (flag_2=1)) then do;
       zSum+1;
       zOne+1;
       output;
   end;
run;

[naveen_srini]

@Syndey , Here you go if you fancy using DO LOOP:

data have; /*Your sample test dataset*/

input Cust $ Rank Flag_1 Flag_2;

cards;

A 1 1 0

A 2 1 1

A 3 1 1

A 4 0 1

A 5 0 1

A 6 1 0

A 7 0 0

B 1 1 0

B 2 1 0

B 3 0 0

;

run;

proc sort data=have;

by cust rank;

run;

data want(drop=n); /*Your Output wanted dataset*/

n=0;

do until(last.cust);

  set have;

  by cust;

  n+1;

end;

do _n_=1 by 1 until(last.cust);

  set have;

  by cust;

  if _n_ in (1,2) or _n_=n-1 or _n_=n then output;

end;

run;

Naveen Srinivasan

L&T Infotech

[Ksharp]

I don't see one observation that has flag_2=1 and flag__1=0  within the obs marked in red .