how to compare date

[xiangpang]

Hello,

I am trying to compare different date. I have two questions here. 

1. how to compare those date and conclude as shown in 'want'?

2. the original data is same as shown in 'dataline'. How could I input the date2 as numeric?

thanks 

dataline
id date1 $ date2  ;

1 05/21/2010 2013-03-21
2 2011-03-01 2011-01-21
3 2014-03    2011
4 2015-01    2015-05
;
run;

want
1 late
2 early
3 early
4 late

[Tom · Accepted solution]

The ANYDTDTE informat can read a lot of different date strings. But it doesn't handle a bare 4 digit year. So add a little more logic to handle those cases.

data have;
  input id date1 date2 @1 id cdate1 :$10. cdate2 :$10.;
  informat date1 date2 anydtdte. ;
  format date1 date2 yymmdd10. ;
  if length(cdate1)=4 then date1=mdy(1,1,input(cdate1,4.));
  if length(cdate2)=4 then date2=mdy(1,1,input(cdate2,4.));
  if date2 < date1 then want='early';
  else want='late';
datalines;
1 05/21/2010 2013-03-21
2 2011-03-01 2011-01-21
3 2014-03    2011
4 2015-01    2015-05
;

Obs    id         date1         date2      cdate1      cdate2        want

 1      1    2010-05-21    2013-03-21    05/21/2010    2013-03-21    late
 2      2    2011-03-01    2011-01-21    2011-03-01    2011-01-21    early
 3      3    2014-03-01    2011-01-01    2014-03       2011          early
 4      4    2015-01-01    2015-05-01    2015-01       2015-05       late

[xiangpang]

thanks for reply. if one cdate1 is 2014-03 and another cdate1 is 2014-04, could I convert them to date1 as 2014-03-31 and date1 as 2014-4-30 instead of 01-01?

[PGStats]

---

@xiangpang wrote:

thanks for reply. if one cdate1 is 2014-03 and another cdate1 is 2014-04, could I convert them to date1 as 2014-03-31 and date1 as 2014-4-30 instead of 01-01?

---

Add the statements

if length(cdate1)=7 then date1 = intnx("month", date1, 0, "END"); 
if length(cdate2)=7 then date2 = intnx("month", date2, 0, "END"); 

[xiangpang]

Thanks a lot. it is what I want.

[Jagadishkatam]

please try the below code 

if there is only year like 2011 then I imputed it to 01-01, let me know if that works for the other imputation suggested is followed.

data have;
  input id date1 $10. date2 $11. ;
  if length(date1)<10 then cd1=intnx('month',input(cats(date1,'-01'),yymmdd10.),0,'e');
 else if length(date1)>=10 then cd1=input(date1,anydtdte10.);

     if length(date2)<=4 then cd2=intnx('year',input(cats(date2,'-01-01'),yymmdd10.),0,'s');
	else if 4< length(date2)<10 then cd2=intnx('month',input(cats(date2,'-01'),yymmdd10.),0,'e');
   else if length(date2)>=10 then cd2=input(date2,anydtdte10.);
   if cd2<cd1 then want='early';
   else want='late';
  format cd: date9.;
datalines;
1 05/21/2010 2013-03-21
2 2011-03-01 2011-01-21
3 2014-03    2011
4 2015-01    2015-05
;

[xiangpang]

Thanks a lot. I learned intnx function from you guys. I did not know that before. 

Have a good day.