Determining continuous enrollment for 6 months

[Sam_I_am]

I have a dataset that looks similar to this

MemberID   StartDate1   EndDate1    Startdate2     Enddate2 StartDate3 EndDate3...StartDate20 Enddate20 

 XXXXXX     01Jun2013  30Jul2015 

 XXXXXX     01Aug2015 31Dec2016   01Feb2017    01Sep2017

 XXXXXX     15Jan2012  15Dec2017

 XXXXXX     01Jan2014  01May2014  15June2014  15Aug2016

I have to determine 6 months of continuous enrollment with an allowable gap of 45 days during a two year measure period, lets say Jan 01 2015-Dec 31, 2017. There is no anchor date. So essentially, I want to check all enrollment dates between Jan 01 2015 and December 31st 2017 and see if they have at least 6 months of continuous enrollment. I'm not sure how to approach this when there are multiple start and end dates. Does anyone have any suggestions?

[Reeza]

Post some more example data and the corresponding expected output. 

If you search on here, it's been answered multiple times, but with a different data structure, a long rather than wide data set.

[s_lassen]

Something like this may work (not tested):

data want;
  set have;
  array startdates startdate1-startdate20;
  array enddates enddate1-enddate20;
  enrolled=0;
  do _N_=1 to dim(startdates); /* find first enrollment within interval */
    if '01jan2015'd<=enddates(_N_)<='31dec2017'd or
       '01jan2015'd<=startdates(_N_)<='31dec2017'd
       then do;
      enroll_from=max(startdates(_N_),'01jan2015'd);
      enroll_to=min(enddates(_N_),'31dec2017'd);
      enrolled=intck('month',enroll_from,enroll_to,'C')>=6;
      leave;
      end;
    end;
  do _N_=_N_+1 to dim(startdates) while(not enrolled);
    if startdates(_N_)>'31dec20017'd then
      leave;
    if startdates(_N_)-enroll_to>45 then
      enroll_from=startdates(_N_);
    enroll_to=min(enddates(_N_),'31dec2017'd);
    enrolled=intck('month',enroll_from,enroll_to,'C')>=6;
    end;
  drop enroll_from enroll_to;
run;