topic For each patient, keep only paired records by date and then do counts based on # of contiguous pairs in SAS Programming

For each patient, keep only paired records by date and then do counts based on # of contiguous pairs

WAL83 — Thu, 16 Feb 2017 00:33:37 GMT

Hello,

I'm trying to determine the number of patients in my dataset that have at least X contiguos paired records by date (DAY & NIGHT RECORD=PAIR). I need to delete records that do not have a PAIR and then create "PAIR#" value to flag contiguous records for the patient. PAIR# = 3 would indicate this is the 3rd contiguous PAIR of records for this patient. Start "PAIR#" over again at 1 if there are non-contiguous paired date records for a patient, in other words PAIR# does not have to be unique for a patient. See below example dataset.

ID	*PAIR#*	*Start Date*	*Start Time*	*Value*	*Delete?*
1		12-Feb-14	6:00:00	DAY	DELETE
1	1	12-Feb-14	6:01:00	DAY	KEEP
1	1	12-Feb-14	22:00:00	NIGHT	KEEP
1	2	13-Feb-14	6:00:00	DAY	KEEP
1	2	13-Feb-14	22:00:00	NIGHT	KEEP
1	3	14-Feb-14	6:00:00	DAY	KEEP
1	3	14-Feb-14	22:00:00	NIGHT	KEEP
3		16-Jan-13	22:00:00	NIGHT	DELETE
3	1	17-Jan-13	6:00:00	DAY	KEEP
3	1	17-Jan-13	22:00:00	NIGHT	KEEP
3		18-Jan-13	22:00:00	NIGHT	DELETE
3		21-Jan-13	22:00:00	NIGHT	DELETE
3	1	22-Jan-13	6:00:00	DAY	KEEP
3	1	22-Jan-13	22:00:00	NIGHT	KEEP
3	2	23-Jan-13	6:00:00	DAY	KEEP
3	2	23-Jan-13	22:00:00	NIGHT	KEEP
4		9-Jan-13	22:00:00	NIGHT	DELETE
4		10-Jan-13	22:00:00	NIGHT	DELETE
4	1	11-Jan-13	6:01:00	DAY	KEEP
4	1	11-Jan-13	22:00:00	NIGHT	KEEP
4	2	12-Jan-13	6:01:00	DAY	KEEP
4	2	12-Jan-13	22:00:00	NIGHT	KEEP
5	1	20-Feb-13	22:00:00	NIGHT	KEEP
5	1	20-Feb-13	6:01:00	DAY	KEEP
5		22-Feb-13	22:00:00	NIGHT	DELETE
5		24-Feb-13	22:00:00	NIGHT	DELETE
5	1	6-Mar-13	6:01:00	DAY	KEEP
5	1	6-Mar-13	22:00:00	NIGHT	KEEP
5	2	7-Mar-13	6:01:00	DAY	KEEP
5	2	7-Mar-13	22:00:00	NIGHT	KEEP
6	1	4-Oct-13	6:00:00	DAY	KEEP
6	1	4-Oct-13	22:00:00	NIGHT	KEEP
6	2	5-Oct-13	6:00:00	DAY	KEEP
6	2	5-Oct-13	22:00:00	NIGHT	KEEP
6		7-Oct-13	6:00:00	DAY	DELETE

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

art297 — Thu, 16 Feb 2017 01:39:50 GMT

I think that the following does what you want:

data want (drop=_:);
  set have;
  by id;
  retain _next_keep pair;
  if first.id then pair=0;
  if not last.id then do;
    _next=_n_+1;
    set have (keep=start_date value
         rename=(start_date=_next_start
                 value=_next_value)) point=_next;
    if _next_keep='KEEP' then do;
      output;
      _next_keep='DELETE';
    end;
    else if start_date eq _next_start and
            value eq 'DAY' and
            _next_value eq 'NIGHT' then do;
      pair+1;
      output;
      _next_keep='KEEP';
    end;
    else _next_keep='DELETE';
  end;
  else if _next_keep eq 'KEEP' then do;
    output;
    _next_keep='DELETE';
  end;
run;

HTH,

Art, CEO, AnalystFinder.com

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

mkeintz — Thu, 16 Feb 2017 01:45:59 GMT

You identify pairs as any two consecutive records with the same id, same start_date, in which one record has value='DAY' and the other has value='NIGHT', in any order.

A pair is assigned a pair number, in which the first pair for an id is pair=1, and subsequent pairs are 2, 3, 4, ... EXCEPT if a given pair is NOT exactly one day after the previous pair, then it is reset to pair=1.

data have;
  input (ID _PAIR) (1. +1 1.) Start_Date :date9. Start_Time time8.0 Value :$5.  _Delete $6.;
  format start_date date9. start_time time8.0;
datalines;
1   12-Feb-14 6:00:00 DAY DELETE 
1 1 12-Feb-14 6:01:00 DAY KEEP 
1 1 12-Feb-14 22:00:00 NIGHT KEEP 
1 2 13-Feb-14 6:00:00 DAY KEEP 
1 2 13-Feb-14 22:00:00 NIGHT KEEP 
1 3 14-Feb-14 6:00:00 DAY KEEP 
1 3 14-Feb-14 22:00:00 NIGHT KEEP 
3   16-Jan-13 22:00:00 NIGHT DELETE 
3 1 17-Jan-13 6:00:00 DAY KEEP 
3 1 17-Jan-13 22:00:00 NIGHT KEEP 
3   18-Jan-13 22:00:00 NIGHT DELETE 
3   21-Jan-13 22:00:00 NIGHT DELETE 
3 1 22-Jan-13 6:00:00 DAY KEEP 
3 1 22-Jan-13 22:00:00 NIGHT KEEP 
3 2 23-Jan-13 6:00:00 DAY KEEP 
3 2 23-Jan-13 22:00:00 NIGHT KEEP 
4   9-Jan-13 22:00:00 NIGHT DELETE 
4   10-Jan-13 22:00:00 NIGHT DELETE 
4 1 11-Jan-13 6:01:00 DAY KEEP 
4 1 11-Jan-13 22:00:00 NIGHT KEEP 
4 2 12-Jan-13 6:01:00 DAY KEEP 
4 2 12-Jan-13 22:00:00 NIGHT KEEP 
5 1 20-Feb-13 22:00:00 NIGHT KEEP 
5 1 20-Feb-13 6:01:00 DAY KEEP 
5   22-Feb-13 22:00:00 NIGHT DELETE 
5   24-Feb-13 22:00:00 NIGHT DELETE 
5 1 6-Mar-13 6:01:00 DAY KEEP 
5 1 6-Mar-13 22:00:00 NIGHT KEEP 
5 2 7-Mar-13 6:01:00 DAY KEEP 
5 2 7-Mar-13 22:00:00 NIGHT KEEP 
6 1 4-Oct-13 6:00:00 DAY KEEP 
6 1 4-Oct-13 22:00:00 NIGHT KEEP 
6 2 5-Oct-13 6:00:00 DAY KEEP 
6 2 5-Oct-13 22:00:00 NIGHT KEEP 
6   7-Oct-13 6:00:00 DAY DELETE 
run;
data want (drop=p nxt_val p_membr);

  set have (keep=id start_date);
  by id start_date;

  retain p 0       /* to track pair number */
         p_membr . /* 1=beginning of pair, 2=end of a pair */;

  if first.start_date then do until (1);
    if not(first.id=1 or lag(start_date)<start_date-1) then leave;
    p=0;
    p_membr=.;
  end;

  merge have 
        have (firstobs=2 keep=id value rename=(value=nxt_val));

  /* If last record was p_membr=1, this one is p_membr=2*/
  if p_membr=1 then do;
    pair=p;
	p_membr=2;
  end;
  else if last.start_date=0 and catx('/',value,nxt_val) in ('DAY/NIGHT','NIGHT/DAY') then do;
	p=p+1;
	pair=p;
	p_membr=1;
  end;
  else p_membr=.;
    
  if p_membr=. then action='DELETE';
  else action='KEEP';
run;

NOtes:

The set with BY statement is just used to determine first.id, first.start_date, and corresponding last.'s
The self merge has firstobs=2 so that one can look ahead at the next records VALUE variable, renamed to "nxt_val".
P_MEMBR=1 for the first record in a pair, and p_membr=2 for the 2nd. Since p_membr is a "retained" value, if it's a one, then the prior record was the beginning of a pair, and current record must be the end of the pair.

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

rogerjdeangelis — Thu, 16 Feb 2017 15:35:11 GMT

This may be related to the solution you want. Did not see a example of output

data have;
  input (ID _PAIR) (1. +1 1.) Start_Date :date9. Start_Time time8.0 Value :$5.  _Delete $6.;
  format start_date date9. start_time time8.0;
  if _pair ne '' then do;
     input #1 (ID _PAIR) (1. +1 1.) Start_Date :date9. Start_Time time8.0 Value :$5.  _Delete $6.
           #2 (xID x_PAIR) (1. +1 1.) xStart_Date :date9. xStart_Time time8.0 xValue :$5.  x_Delete $6.;
     if value='DAY' and xvalue='NIGHT' then output;
  end;
cards4;
1   12-Feb-14 6:00:00 DAY DELETE
1 1 12-Feb-14 6:01:00 DAY KEEP
1 1 12-Feb-14 22:00:00 NIGHT KEEP
1 2 13-Feb-14 6:00:00 DAY KEEP
1 2 13-Feb-14 22:00:00 NIGHT KEEP
1 3 14-Feb-14 6:00:00 DAY KEEP
1 3 14-Feb-14 22:00:00 NIGHT KEEP
3   16-Jan-13 22:00:00 NIGHT DELETE
3 1 17-Jan-13 6:00:00 DAY KEEP
3 1 17-Jan-13 22:00:00 NIGHT KEEP
3   18-Jan-13 22:00:00 NIGHT DELETE
3   21-Jan-13 22:00:00 NIGHT DELETE
3 1 22-Jan-13 6:00:00 DAY KEEP
3 1 22-Jan-13 22:00:00 NIGHT KEEP
3 2 23-Jan-13 6:00:00 DAY KEEP
3 2 23-Jan-13 22:00:00 NIGHT KEEP
4   9-Jan-13 22:00:00 NIGHT DELETE
4   10-Jan-13 22:00:00 NIGHT DELETE
4 1 11-Jan-13 6:01:00 DAY KEEP
4 1 11-Jan-13 22:00:00 NIGHT KEEP
4 2 12-Jan-13 6:01:00 DAY KEEP
4 2 12-Jan-13 22:00:00 NIGHT KEEP
5 1 20-Feb-13 22:00:00 NIGHT KEEP
5 1 20-Feb-13 6:01:00 DAY KEEP
5   22-Feb-13 22:00:00 NIGHT DELETE
5   24-Feb-13 22:00:00 NIGHT DELETE
5 1 6-Mar-13 6:01:00 DAY KEEP
5 1 6-Mar-13 22:00:00 NIGHT KEEP
5 2 7-Mar-13 6:01:00 DAY KEEP
5 2 7-Mar-13 22:00:00 NIGHT KEEP
6 1 4-Oct-13 6:00:00 DAY KEEP
6 1 4-Oct-13 22:00:00 NIGHT KEEP
6 2 5-Oct-13 6:00:00 DAY KEEP
6 2 5-Oct-13 22:00:00 NIGHT KEEP
6   7-Oct-13 6:00:00 DAY DELETE
;;;;
run;quit;

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

WAL83 — Thu, 16 Feb 2017 17:10:51 GMT

My aplogies for not including an example output dataset. Also it may be easier to understand my goal if I only include variables available in my dataset.

data have;

input ID 4. Start_Date :date9. Start_Time time8.0 End_Time time8.0 Value :$5.;

format Start_Date date9. Start_Time time8.0 End_time time8.0;

datalines;

1024 22-Feb-14 6:00 21:59 DAY

1024 22-Feb-14 22:00 5:59 NIGHT

1024 23-Feb-14 6:00 21:59 DAY

1024 23-Feb-14 22:00 5:59 NIGHT

1024 24-Feb-14 6:00 21:59 DAY

1024 24-Feb-14 22:00 5:59 NIGHT

1040 3-Apr-14 6:00 21:59 DAY

1040 3-Apr-14 22:00 5:59 NIGHT

1040 4-Apr-14 22:00 5:59 NIGHT

1040 5-Apr-14 6:00 21:59 DAY

1040 5-Apr-14 22:00 5:59 NIGHT

1040 6-Apr-14 22:00 5:59 NIGHT

1040 7-Apr-14 6:00 21:59 DAY

1040 7-Apr-14 22:00 5:59 NIGHT

2003 1-Jul-13 6:00 21:59 DAY

2003 1-Jul-13 22:00 5:59 NIGHT

2003 2-Jul-13 22:00 5:59 NIGHT

2003 3-Jul-13 6:00 21:59 DAY

2003 3-Jul-13 22:00 5:59 NIGHT

2003 4-Jul-13 6:00 21:59 DAY

2003 4-Jul-13 22:00 5:59 NIGHT

2003 5-Jul-13 6:00 21:59 DAY

2010 2-Jun-13 6:01 21:59 DAY

2010 2-Jun-13 22:00 6:00 NIGHT

2010 16-Jul-13 6:01 21:59 DAY

2010 16-Jul-13 22:00 6:00 NIGHT

2010 17-Jul-13 6:01 21:59 DAY

2010 17-Jul-13 22:00 6:00 NIGHT

2010 24-Jul-13 6:01 21:59 DAY

2010 24-Jul-13 22:00 6:00 NIGHT

2010 25-Jul-13 22:00 6:00 NIGHT

2010 26-Jul-13 22:00 6:00 NIGHT

2010 28-Jul-13 22:00 6:00 NIGHT

2010 29-Jul-13 6:01 21:59 DAY

2010 29-Jul-13 22:00 6:00 NIGHT

2010 1-Aug-13 6:01 21:59 DAY

2010 9-Aug-13 6:01 21:59 DAY

2010 9-Aug-13 22:00 6:00 NIGHT

2010 10-Aug-13 6:01 21:59 DAY

2010 10-Aug-13 22:00 6:00 NIGHT

2010 11-Aug-13 22:00 6:00 NIGHT

2010 12-Aug-13 22:00 6:00 NIGHT

2010 1-Mar-14 22:00 5:59 NIGHT

2010 2-Mar-14 22:00 5:59 NIGHT

2010 3-Mar-14 22:00 5:59 NIGHT

2010 5-Mar-14 6:00 21:59 DAY

2010 5-Mar-14 22:00 5:59 NIGHT

2010 6-Mar-14 6:00 21:59 DAY

2010 6-Mar-14 22:00 5:59 NIGHT

run;

Output dataset with addition of 2 new variables added (Action, Pair).

*Action*	*Pair*	ID	Start Date	Start Time	End Time	Value
KEEP	1	1024	22-Feb-14	6:00	21:59	DAY
KEEP	1	1024	22-Feb-14	22:00	5:59	NIGHT
KEEP	2	1024	23-Feb-14	6:00	21:59	DAY
KEEP	2	1024	23-Feb-14	22:00	5:59	NIGHT
KEEP	3	1024	24-Feb-14	6:00	21:59	DAY
KEEP	3	1024	24-Feb-14	22:00	5:59	NIGHT
KEEP	1	1040	3-Apr-14	6:00	21:59	DAY
KEEP	1	1040	3-Apr-14	22:00	5:59	NIGHT
DELETE	.	1040	4-Apr-14	22:00	5:59	NIGHT
KEEP	1	1040	5-Apr-14	6:00	21:59	DAY
KEEP	1	1040	5-Apr-14	22:00	5:59	NIGHT
DELETE	.	1040	6-Apr-14	22:00	5:59	NIGHT
KEEP	1	1040	7-Apr-14	6:00	21:59	DAY
KEEP	1	1040	7-Apr-14	22:00	5:59	NIGHT
KEEP	1	2003	1-Jul-13	6:00	21:59	DAY
KEEP	1	2003	1-Jul-13	22:00	5:59	NIGHT
DELETE	.	2003	2-Jul-13	22:00	5:59	NIGHT
KEEP	1	2003	3-Jul-13	6:00	21:59	DAY
KEEP	1	2003	3-Jul-13	22:00	5:59	NIGHT
KEEP	2	2003	4-Jul-13	6:00	21:59	DAY
KEEP	2	2003	4-Jul-13	22:00	5:59	NIGHT
DELETE	.	2003	5-Jul-13	6:00	21:59	DAY
KEEP	1	2010	2-Jun-13	6:01	21:59	DAY
KEEP	1	2010	2-Jun-13	22:00	6:00	NIGHT
KEEP	1	2010	16-Jul-13	6:01	21:59	DAY
KEEP	1	2010	16-Jul-13	22:00	6:00	NIGHT
KEEP	2	2010	17-Jul-13	6:01	21:59	DAY
KEEP	2	2010	17-Jul-13	22:00	6:00	NIGHT
KEEP	3	2010	24-Jul-13	6:01	21:59	DAY
KEEP	3	2010	24-Jul-13	22:00	6:00	NIGHT
DELETE	.	2010	25-Jul-13	22:00	6:00	NIGHT
DELETE	.	2010	26-Jul-13	22:00	6:00	NIGHT
DELETE	.	2010	28-Jul-13	22:00	6:00	NIGHT
KEEP	1	2010	29-Jul-13	6:01	21:59	DAY
KEEP	1	2010	29-Jul-13	22:00	6:00	NIGHT
DELETE	.	2010	1-Aug-13	6:01	21:59	DAY
KEEP	1	2010	9-Aug-13	6:01	21:59	DAY
KEEP	1	2010	9-Aug-13	22:00	6:00	NIGHT
KEEP	2	2010	10-Aug-13	6:01	21:59	DAY
KEEP	2	2010	10-Aug-13	22:00	6:00	NIGHT
DELETE	.	2010	11-Aug-13	22:00	6:00	NIGHT
DELETE	.	2010	12-Aug-13	22:00	6:00	NIGHT
DELETE	.	2010	1-Mar-14	22:00	5:59	NIGHT
DELETE	.	2010	2-Mar-14	22:00	5:59	NIGHT
DELETE	.	2010	3-Mar-14	22:00	5:59	NIGHT
KEEP	1	2010	5-Mar-14	6:00	21:59	DAY
KEEP	1	2010	5-Mar-14	22:00	5:59	NIGHT
KEEP	2	2010	6-Mar-14	6:00	21:59	DAY
KEEP	2	2010	6-Mar-14	22:00	5:59	NIGHT

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

art297 — Thu, 16 Feb 2017 19:13:18 GMT

The code I originally suggested assumed that you actually wanted to delete those records. The following does what you are currently asking for:

data want (drop=_:);
  set have;
  by id;
  length action $6;
  retain _next_keep pair;
  if first.id then pair=0;
  if not last.id then do;
    _next=_n_+1;
    set have (keep=start_date value
         rename=(start_date=_next_start
                 value=_next_value)) point=_next;
    if _next_keep='KEEP' then do;
      action='KEEP';
      output;
      _next_keep='DELETE';
    end;
    else if start_date eq _next_start and
            value eq 'DAY' and
            _next_value eq 'NIGHT' then do;
      pair+1;
      action='KEEP';
      output;
      _next_keep='KEEP';
    end;
    else do;
      action='DELETE';
      output;
      _next_keep='DELETE';
    end;
  end;
  else if _next_keep eq 'KEEP' then do;
    action='KEEP';
    output;
    _next_keep='DELETE';
  end;
run;

HTH,

Art, CEO, AnalystFinder.com

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

WAL83 — Thu, 16 Feb 2017 23:00:35 GMT

Thanks for the quick reply. Your adjusted code achieves all my goals except reset pair count to 1 if there are non-contiguous date records. See records in bold red in below example output dataset.

*Action*	*Pair*	ID	Start Date	Start Time	End Time	Value
KEEP	1	1024	22-Feb-14	6:00	21:59	DAY
KEEP	1	1024	22-Feb-14	22:00	5:59	NIGHT
KEEP	2	1024	23-Feb-14	6:00	21:59	DAY
KEEP	2	1024	23-Feb-14	22:00	5:59	NIGHT
KEEP	3	1024	24-Feb-14	6:00	21:59	DAY
KEEP	3	1024	24-Feb-14	22:00	5:59	NIGHT
KEEP	1	1040	3-Apr-14	6:00	21:59	DAY
KEEP	1	1040	3-Apr-14	22:00	5:59	NIGHT
DELETE	.	1040	4-Apr-14	22:00	5:59	NIGHT
KEEP	1	1040	5-Apr-14	6:00	21:59	DAY
KEEP	1	1040	5-Apr-14	22:00	5:59	NIGHT
DELETE	.	1040	6-Apr-14	22:00	5:59	NIGHT
KEEP	1	1040	7-Apr-14	6:00	21:59	DAY
KEEP	1	1040	7-Apr-14	22:00	5:59	NIGHT
KEEP	1	2003	1-Jul-13	6:00	21:59	DAY
KEEP	1	2003	1-Jul-13	22:00	5:59	NIGHT
DELETE	.	2003	2-Jul-13	22:00	5:59	NIGHT
KEEP	1	2003	3-Jul-13	6:00	21:59	DAY
KEEP	1	2003	3-Jul-13	22:00	5:59	NIGHT
KEEP	2	2003	4-Jul-13	6:00	21:59	DAY
KEEP	2	2003	4-Jul-13	22:00	5:59	NIGHT
DELETE	.	2003	5-Jul-13	6:00	21:59	DAY
KEEP	1	2010	2-Jun-13	6:01	21:59	DAY
KEEP	1	2010	2-Jun-13	22:00	6:00	NIGHT
KEEP	1	2010	16-Jul-13	6:01	21:59	DAY
KEEP	1	2010	16-Jul-13	22:00	6:00	NIGHT
KEEP	2	2010	17-Jul-13	6:01	21:59	DAY
KEEP	2	2010	17-Jul-13	22:00	6:00	NIGHT
KEEP	3	2010	24-Jul-13	6:01	21:59	DAY
KEEP	3	2010	24-Jul-13	22:00	6:00	NIGHT
DELETE	.	2010	25-Jul-13	22:00	6:00	NIGHT
DELETE	.	2010	26-Jul-13	22:00	6:00	NIGHT
DELETE	.	2010	28-Jul-13	22:00	6:00	NIGHT
KEEP	1	2010	29-Jul-13	6:01	21:59	DAY
KEEP	1	2010	29-Jul-13	22:00	6:00	NIGHT
DELETE	.	2010	1-Aug-13	6:01	21:59	DAY
KEEP	1	2010	9-Aug-13	6:01	21:59	DAY
KEEP	1	2010	9-Aug-13	22:00	6:00	NIGHT
KEEP	2	2010	10-Aug-13	6:01	21:59	DAY
KEEP	2	2010	10-Aug-13	22:00	6:00	NIGHT
DELETE	.	2010	11-Aug-13	22:00	6:00	NIGHT
DELETE	.	2010	12-Aug-13	22:00	6:00	NIGHT
DELETE	.	2010	1-Mar-14	22:00	5:59	NIGHT
DELETE	.	2010	2-Mar-14	22:00	5:59	NIGHT
DELETE	.	2010	3-Mar-14	22:00	5:59	NIGHT
KEEP	1	2010	5-Mar-14	6:00	21:59	DAY
KEEP	1	2010	5-Mar-14	22:00	5:59	NIGHT
KEEP	2	2010	6-Mar-14	6:00	21:59	DAY
KEEP	2	2010	6-Mar-14	22:00	5:59	NIGHT

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

art297 — Thu, 16 Feb 2017 23:39:08 GMT

I question your pair assignment for the following two records:

KEEP	3	2010	24-Jul-13	6:01	21:59	DAY
KEEP	3	2010	24-Jul-13	22:00	6:00	NIGHT

according to your rules, I'd think they should be 1s.

If so, the following should work:

data want (drop=_:);
  set have;
  by id;
  length action $6;
  retain _next_keep _last_kept_date _pair;
  if first.id then _pair=0;
  if not last.id then do;
    _next=_n_+1;
    set have (keep=start_date value
         rename=(start_date=_next_start
                 value=_next_value)) point=_next;
    if _next_keep='KEEP' then do;
      action='KEEP';
      _last_kept_date=start_date;
      pair=_pair;
      output;
      _next_keep='DELETE';
    end;
    else if start_date eq _next_start and
            value eq 'DAY' and
            _next_value eq 'NIGHT' then do;
      if 0<=(start_date-_last_kept_date)<=1 then _pair+1;
      else _pair=1;
      pair=_pair;
      action='KEEP';
      output;
      _next_keep='KEEP';
    end;
    else do;
      action='DELETE';
      output;
      _next_keep='DELETE';
    end;
  end;
  else if _next_keep eq 'KEEP' then do;
    action='KEEP';
    pair=_pair;
    output;
    _next_keep='DELETE';
  end;
run;

HTH,

Art, CEO, AnalystFinder.com

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

mkeintz — Thu, 16 Feb 2017 23:43:14 GMT

This code produces what you want, includng the reset to pair=1 when a pair is more than one day after the most preceding pair.

HOWEVER, it appears your sample answer is wrong for the 24-July-2013 pair, which you have assigned as pair=3. But the preceding pair is 1 week prior (17-JUL-13), so the 24-jul pair should be pair=1.

data want (drop=p nxt_val p_membr pair_date);

  set have (keep=id start_date);
  by id start_date;

  retain p 0       /* to track pair number */
         p_membr . /* 1=beginning of pair, 2=end of a pair */
         pair_date /* Date of most recent pair */

  if first.start_date=1 then do;
    if first.id then p=0;
    if pair_date < start_date-1 then p=0;
  end;

  merge have 
        have (firstobs=2 keep=id value rename=(value=nxt_val));

  /* If retain p_membr=1, this one must be p_membr=2*/
  if p_membr=1 then do;
    pair=p;
    p_membr=2;
  end;
  else if last.start_date=0 and catx('/',value,nxt_val) in ('DAY/NIGHT','NIGHT/DAY') then do;
    p_membr=1;
    pair_date=start_date;
    p=p+1;
    pair=p;
  end;
  else p_membr=.;
    
  if p_membr=. then action='DELETE';
  else action='KEEP';

run;

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

WAL83 — Thu, 16 Feb 2017 23:56:58 GMT

Aye, yes you are correct. Long day 😞

Your code does work very well although it renumbers the last pair id to the next id.. See example output dataset below...

ID	Start_Date	Start_Time	End_Time	Value	pair	action
1024	22-Feb-14	6:00:00	21:59:00	DAY	1	KEEP
1024	22-Feb-14	22:00:00	5:59:00	NIGHT	1	KEEP
1024	23-Feb-14	6:00:00	21:59:00	DAY	2	KEEP
1024	23-Feb-14	22:00:00	5:59:00	NIGHT	2	KEEP
1024	24-Feb-14	6:00:00	21:59:00	DAY	3	KEEP
1040	24-Feb-14	22:00:00	5:59:00	NIGHT	3	KEEP
1040	3-Apr-14	6:00:00	21:59:00	DAY	1	KEEP
1040	3-Apr-14	22:00:00	5:59:00	NIGHT	1	KEEP
1040	4-Apr-14	22:00:00	5:59:00	NIGHT	.	DELETE
1040	5-Apr-14	6:00:00	21:59:00	DAY	2	KEEP
1040	5-Apr-14	22:00:00	5:59:00	NIGHT	2	KEEP
1040	6-Apr-14	22:00:00	5:59:00	NIGHT	.	DELETE
1040	7-Apr-14	6:00:00	21:59:00	DAY	3	KEEP
2003	7-Apr-14	22:00:00	5:59:00	NIGHT	3	KEEP
2003	1-Jul-13	6:00:00	21:59:00	DAY	1	KEEP
2003	1-Jul-13	22:00:00	5:59:00	NIGHT	1	KEEP
2003	2-Jul-13	22:00:00	5:59:00	NIGHT	.	DELETE
2003	3-Jul-13	6:00:00	21:59:00	DAY	2	KEEP
2003	3-Jul-13	22:00:00	5:59:00	NIGHT	2	KEEP
2003	4-Jul-13	6:00:00	21:59:00	DAY	3	KEEP
2003	4-Jul-13	22:00:00	5:59:00	NIGHT	3	KEEP
2010	5-Jul-13	6:00:00	21:59:00	DAY	.	DELETE
2010	2-Jun-13	6:01:00	21:59:00	DAY	1	KEEP
2010	2-Jun-13	22:00:00	6:00:00	NIGHT	1	KEEP
2010	16-Jul-13	6:01:00	21:59:00	DAY	1	KEEP
2010	16-Jul-13	22:00:00	6:00:00	NIGHT	1	KEEP
2010	17-Jul-13	6:01:00	21:59:00	DAY	2	KEEP
2010	17-Jul-13	22:00:00	6:00:00	NIGHT	2	KEEP
2010	24-Jul-13	6:01:00	21:59:00	DAY	1	KEEP
2010	24-Jul-13	22:00:00	6:00:00	NIGHT	1	KEEP
2010	25-Jul-13	22:00:00	6:00:00	NIGHT	.	DELETE
2010	26-Jul-13	22:00:00	6:00:00	NIGHT	.	DELETE
2010	28-Jul-13	22:00:00	6:00:00	NIGHT	.	DELETE
2010	29-Jul-13	6:01:00	21:59:00	DAY	1	KEEP
2010	29-Jul-13	22:00:00	6:00:00	NIGHT	1	KEEP
2010	1-Aug-13	6:01:00	21:59:00	DAY	.	DELETE
2010	9-Aug-13	6:01:00	21:59:00	DAY	1	KEEP
2010	9-Aug-13	22:00:00	6:00:00	NIGHT	1	KEEP
2010	10-Aug-13	6:01:00	21:59:00	DAY	2	KEEP
2010	10-Aug-13	22:00:00	6:00:00	NIGHT	2	KEEP
2010	11-Aug-13	22:00:00	6:00:00	NIGHT	.	DELETE
2010	12-Aug-13	22:00:00	6:00:00	NIGHT	.	DELETE
2010	1-Mar-14	22:00:00	5:59:00	NIGHT	.	DELETE
2010	2-Mar-14	22:00:00	5:59:00	NIGHT	.	DELETE
2010	3-Mar-14	22:00:00	5:59:00	NIGHT	.	DELETE
2010	5-Mar-14	6:00:00	21:59:00	DAY	1	KEEP
2010	5-Mar-14	22:00:00	5:59:00	NIGHT	1	KEEP
2010	6-Mar-14	6:00:00	21:59:00	DAY	2	KEEP
2010	6-Mar-14	22:00:00	5:59:00	NIGHT	2	KEEP

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

art297 — Fri, 17 Feb 2017 00:01:23 GMT

Did you try my revised code?

Art, CEO, AnalystFinder.com

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

WAL83 — Fri, 17 Feb 2017 00:04:21 GMT

Yes. It works except for the resetting of pair = 1 when non-contiguous date occurs.

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

art297 — Fri, 17 Feb 2017 00:06:42 GMT

Not the code I posted about a half hour ago .. I don't think!

Art, CEO, AnalystFinder.com

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

WAL83 — Fri, 17 Feb 2017 00:16:45 GMT

I think it's working. I'm double checking. I'm getting tired 😞

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

mkeintz — Fri, 17 Feb 2017 00:26:57 GMT

Please mark @art297's message with the working code as the solution, not his request for you to test it.

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

WAL83 — Fri, 17 Feb 2017 00:31:20 GMT

Yes, I did not mean to mark that as accepted. Mouse malfunction...

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

WAL83 — Fri, 17 Feb 2017 00:48:56 GMT

Your code IS resetting pair=1 but it deleted a record for some reason. Original dataset has 49 records, output dataset now has 48. Your code deletes the record in red... It was the last record for that ID and did not have a PAIR...

ID	Start_Date	Start_Time	End_Time	Value
2003	1-Jul-13	6:00:00	21:59:00	DAY
2003	1-Jul-13	22:00:00	5:59:00	NIGHT
2003	2-Jul-13	22:00:00	5:59:00	NIGHT
2003	3-Jul-13	6:00:00	21:59:00	DAY
2003	3-Jul-13	22:00:00	5:59:00	NIGHT
2003	4-Jul-13	6:00:00	21:59:00	DAY
2003	4-Jul-13	22:00:00	5:59:00	NIGHT
2003	5-Jul-13	6:00:00	21:59:00	DAY

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

art297 — Fri, 17 Feb 2017 01:21:41 GMT

Indeed! I missed the case where it was the last.id and started with an otherwise potentially valid record. This code should correct for that:

data want (drop=_:);
  set have;
  by id;
  length action $6;
  retain _next_keep _last_kept_date _pair;
  if first.id then _pair=0;
  if not last.id then do;
    _next=_n_+1;
    set have (keep=start_date value
         rename=(start_date=_next_start
                 value=_next_value)) point=_next;
    if _next_keep='KEEP' then do;
      action='KEEP';
      _last_kept_date=start_date;
      pair=_pair;
      output;
      _next_keep='DELETE';
    end;
    else if start_date eq _next_start and
            value eq 'DAY' and
            _next_value eq 'NIGHT' then do;
      if 0<=(start_date-_last_kept_date)<=1 then _pair+1;
      else _pair=1;
      pair=_pair;
      action='KEEP';
      output;
      _next_keep='KEEP';
    end;
    else do;
      action='DELETE';
      output;
      _next_keep='DELETE';
    end;
  end;
  else do;
    if _next_keep eq 'KEEP' then do;
      action='KEEP';
      pair=_pair;
      output;
      _next_keep='DELETE';
    end;
    else do;
      action='DELETE';
      output;
      _next_keep='DELETE';
    end;
  end;
run;

Art, CEO, AnalystFinder.com

Re: For each patient, keep only paired records by date and then do counts based on # of contiguous p

WAL83 — Fri, 17 Feb 2017 04:32:18 GMT

Thanks for hanging in there!!! I realize what I was asking was not exactly clear at first. Will be more concise the next time. Thanks again!!!!