*Needle in a haystack:  searching for the year
	marital status changes from married to divorced.;

* We use arrays here in a couple of ways.
	First is a recode.  Then we have a temporary array
	for a table lookup of year.  Finally, we pick the year
	based on a search across columns - finding the needle
	in the haystack.;

libname y "y:\sas\arrays";
libname library (y);

data nlswomen;
	set y.nlswomen;
	* for recode;
	array original{*} R0002400 R0133700 R0205100 R0288200 
	R0308300 R0367600 R0455600 R0491300 R0661400 R0666600 R0721700 
	R0869900 R0997700 R1290700 R1664710 R3507200 R4278200 
	R5447500 R6516200;
	array mstatus{19}; *for recoded values;
	do i=1 to dim(original); * this loop does recoding;
		if original{i}=2 then mstatus{i}=1;
		 else mstatus{i} = original{i};
		end;

	* table lookup, to translate waves to years;
	array year{19} _temporary_ (1967 1971 1972 1974 1976 1977 1979 1981 1982 
			1984 1986 1987 1989 1992 1995 1997 1999 2001 2003); *to use in table lookup;
	m2d = 0;
	do i=2 to dim(mstatus); * A loop searching for a specific change in marital status
				from married to divorced;
		if (mstatus{i-1} eq 1 and mstatus{i} eq 4) then do;
			m2d=1;
			yeardiv = year{i};
			end; * because we loop over all the variables, this identifies the
				last time someone goes from married to divored;
		end;
	drop i;		*We might soemtimes want to keep i, it identifies the wave;
	run;

proc freq;
	tables m2d yeardiv;
	run;