Consolidate multiple observations based on validity ranges

[KermitTheFrog]

I need to consolidate observations based on consecutive validity ranges.

Here is a reproducible minimal example:

data have;
infile datalines4 delimiter=",";
input id $ start :date9. end :date9. var1 var2 var3;
format start end date9.;
datalines4;
ABC1,01DEC2020,21FEB2021,1,0,1
ABC1,22FEB2021,10MAR2021,1,0,1
ABC1,11MAR2021,31DEC9999,1,1,1
DEF2,11DEC2020,10JAN2021,0,0,0
DEF2,11JAN2021,19JAN2021,1,1,1
DEF2,20JAN2021,02FEB2021,1,1,1
DEF2,03FEB2021,10MAR2025,1,0,1
;;;;
quit;

For each id, if the validity dates are consecutive (i.e. end_date + 1day of the n-1 observation is equal to the start_date of the n observation) and if they share the same value for all three variables (var1, var2 and var3), I want to consolidate those multiple observations into a single one.

What I would like to have:

Any kind of approach (array/hash/sql) would be appreciated !

[ChrisNZ]

Like this?

data HAVE;
  infile datalines4 delimiter=",";
  input ID $ START :date9. END :date9. VAR1 VAR2 VAR3;
  format START END date9.;
datalines4;
ABC1,01DEC2020,21FEB2021,1,0,1
ABC1,22FEB2021,10MAR2021,1,0,1
ABC1,11MAR2021,31DEC9999,1,1,1
DEF2,11DEC2020,10JAN2021,0,0,0
DEF2,11JAN2021,19JAN2021,1,1,1
DEF2,20JAN2021,01FEB2021,1,1,1
DEF2,02FEB2021,02FEB2021,1,1,1
DEF2,03FEB2021,10MAR2025,1,0,1
run;

data WANT;
  set HAVE end=LASTOBS;
  if ^LASTOBS then set HAVE 
    (firstobs=2
     rename=(ID=_ID START=_START END=_END VAR1=_VAR1 VAR2=_VAR2 VAR3=_VAR3)) ;
  _SAMEVALUES= ( ID=_ID & VAR1=_VAR1 & VAR2=_VAR2 & VAR3=_VAR3);
  if LASTOBS | ^_SAMEVALUES then do;
    START=coalesce(_S,START);
    output;
    _S=.;
  end;
  else if ^_S then _S=START;   
  retain _S;   
  drop  _:;
run;

ID	START	END	VAR1	VAR2	VAR3
ABC1	01DEC2020	10MAR2021	1	0	1
ABC1	11MAR2021	31DEC9999	1	1	1
DEF2	11DEC2020	10JAN2021	0	0	0
DEF2	11JAN2021	02FEB2021	1	1	1
DEF2	03FEB2021	10MAR2025	1	0	1

[Ksharp · Accepted solution]

data HAVE;
  infile datalines4 delimiter=",";
  input ID $ START :date9. END :date9. VAR1 VAR2 VAR3;
  format START END date9.;
datalines4;
ABC1,01DEC2020,21FEB2021,1,0,1
ABC1,22FEB2021,10MAR2021,1,0,1
ABC1,11MAR2021,31DEC9999,1,1,1
DEF2,11DEC2020,10JAN2021,0,0,0
DEF2,11JAN2021,19JAN2021,1,1,1
DEF2,20JAN2021,01FEB2021,1,1,1
DEF2,02FEB2021,02FEB2021,1,1,1
DEF2,03FEB2021,10MAR2025,1,0,1
;;;;
run;

data temp;
 set have;
 do date=start to end;
  output;
 end;
 drop start end;
 format date date9.;
run;
proc sort data=temp out=temp1 nodupkey;
by id VAR1 VAR2 VAR3 date;
run;
data temp2;
 set temp1;
 by id VAR1 VAR2 VAR3;
 if first.var3 or dif(date) ne 1 then group+1;
run;
proc summary data=temp2;
by  id VAR1 VAR2 VAR3;
var date;
output out=want min=start max=end;
run;