Retain multiple variables and use subset within do loop

[cool1993]

Hello everyone,

My dataset is the following:

Person	Person_num	Year	Firstyear	Company
A	1	2005	1	aa
A	1	2006	0	aa
A	1	2007	0	aa
A	1	2008	0	aa
A	1	2008	0	bb
A	1	2009	0	aa
A	1	2009	0	bb
B	2	2008	1	cc
B	2	2009	0	dd
B	2	2009	0	cc
B	2	2010	0	dd
B	2	2011	0	dd
B	2	2012	0	dd
C	3	2002	1	ee
C	3	2002	1	ff
C	3	2003	0	ee
C	3	2003	0	ff
C	3	2004	0	ff
C	3	2008	0	ff
C	3	2009	0	ff
C	3	2010	0	ff
C	3	2011	0	ff
C	3	2012	0	ff
C	3	2012	0	gg
C	3	2013	0	ff
C	3	2014	0	ff
D	4	2005	1	hh
D	4	2006	0	hh
D	4	2010	0	ii
D	4	2011	0	ii
D	4	2012	0	ii
D	4	2014	0	jj
D	4	2015	0	jj

The expected outcome is the following:

Person	Person_num	Year	Firstyear	Company	Save	Want
A	1	2005	1	aa	aa	1
A	1	2006	0	aa	aa	0
A	1	2007	0	aa	aa	0
A	1	2008	0	aa	aa	0
A	1	2008	0	bb	aa	0
A	1	2009	0	aa	aa	0
A	1	2009	0	bb	aa	0
B	2	2008	1	cc	cc	1
B	2	2009	0	dd	cc	0
B	2	2009	0	cc	cc	0
B	2	2010	0	dd	dd	1
B	2	2011	0	dd	dd	0
B	2	2012	0	dd	dd	0
C	3	2002	1	ee	{ee, ff}	1
C	3	2002	1	ff	{ee, ff}	1
C	3	2003	0	ee	{ee, ff}	0
C	3	2003	0	ff	{ee, ff}	0
C	3	2004	0	ff	ff	0
C	3	2008	0	ff	ff	0
C	3	2009	0	ff	ff	0
C	3	2010	0	ff	ff	0
C	3	2011	0	ff	ff	0
C	3	2012	0	ff	ff	0
C	3	2012	0	gg	ff	0
C	3	2013	0	ff	ff	0
C	3	2014	0	ff	ff	0
D	4	2005	1	hh	hh	1
D	4	2006	0	hh	hh	0
D	4	2010	0	ii	ii	1
D	4	2011	0	ii	ii	0
D	4	2012	0	ii	ii	0
D	4	2014	0	jj	jj	1
D	4	2015	0	jj	jj	0

The logic behind is the following:

1. If firstyear = 1 then want = 1; 
2. If firstyear = 1, save = {companies}. That is, save include all companies when firstyear = 1. (Is it possible to save multiple variables into the save variable?)
3. If firstyear ne 0 and company = lag(save), then save = lag(save) and want = 0;

    else if the company in save then save = lag(save) and want = 0;

    else if, among the same year observations, there is an observation whose company is equal to the current observation's save variable, then save = lag(save) and want = 0;

    else save = code and want = 1;

My attempt is the following:

data have;
input Person $ Person_num Year Firstyear Company $;
datalines;
A	1	2005	1	aa
A	1	2006	0	aa
A	1	2007	0	aa
A	1	2008	0	aa
A	1	2008	0	bb
A	1	2009	0	aa
A	1	2009	0	bb
B	2	2008	1	cc
B	2	2009	0	dd
B	2	2009	0	cc
B	2	2010	0	dd
B	2	2011	0	dd
B	2	2012	0	dd
C	3	2002	1	ee
C	3	2002	1	ff
C	3	2003	0	ee
C	3	2003	0	ff
C	3	2004	0	ff
C	3	2008	0	ff
C	3	2009	0	ff
C	3	2010	0	ff
C	3	2011	0	ff
C	3	2012	0	ff
C	3	2012	0	gg
C	3	2013	0	ff
C	3	2014	0	ff
D	4	2005	1	hh
D	4	2006	0	hh
D	4	2010	0	ii
D	4	2011	0	ii
D	4	2012	0	ii
D	4	2014	0	jj
D	4	2015	0	jj
;

data want; set have;
do i = 1 to 4;
if person_num = i then do;
 	if firstyear = 1 then want = 1 and save = code; *How can assign multiple variables into the save variable when Person = C;
	if firstyear ne 0 and company = lag(save) then save = lag(save) and want = 0;
	else if company in save then save = lag(save) and want = 0;
	else if; *I have no idea in this part.;
	else save = code and want = 1;
end;
end;
run;

[PaigeMiller]

Please show us the desired output.

[cool1993]

Want variable is the desired output.

[34reqrwe]

"If previous year observations within the same identifier include the code(P1), then want variable should be zero." 

Why then does the 4th observation (A, P3, 2002) have want = 1 ? 

[cool1993]

Because obs4's code is P3 (neither P1 nor P2), want variable has the value of 1.

[34reqrwe]

What is the logic for the last observation having want = 0?

[cool1993]

Q) What is the logic for the last observation having want = 0?

A) Since the last observation's code is P11 and the previous observations of the identifier D already have P11, the last want variable should be 0.

[cool1993]

Want variable is not an identifier-level variable. It is an identifier-year-level variable