Gap of at least 30 days

[div44]

Person	Chocolate	Date Received	Date Finished	No chocolate	Actual No chocolate
1	Snickers	7-May-15	11-May-15	0	0
1	MM	8-May-15	13-May-15	0	0
1	Twix	10-May-15	18-May-15	0	0
1	Bounty	12-May-15	16-May-15	0	0
1	Hersheys	17-Jun-15	21-Jun-15	1	0

I need to find when there were at least 30 days without a chocolate for person 1. My current code sorts the data by date received, and gets me the solution to "No chocolate". This is wrong, as it marks the last row as 1, suggesting a difference between (date finsihed - date received for the next chocolate) is 16May15 - 17jun15 = 31 days, however the code does not account for the Bounty choclate date finished which is 18May15, and hence the difference should have been 18May15 - 17Jun15 = 29days and hence does not meet the criteria of at least 30 days as suggested by the Actual No Chocolate column.

Sorting the data by date finshed descending does not help either

Any help would be appreciated thanks

Code

data want;

set have

by person date_received;

gap=date_received-lag(date_finished);

if first.person=1 then no_chocolate=1;

else if gap>=30 then no_chocolate+1;

run;

[PeterClemmensen]

I dont see that the Date finished for the Bounty is 18May15? Isn't that the date finished for the Twix?

[div44]

Yes, it should have been the finished date for Twix.

Thanks for pointing that out.

[DanielSantos]

Hi.

Your code should work, Date Finished of Bounty is 16-May-2015.

data want;

set have

by person date_received;

gap=date_received-lag(date_finished);

if first.person=1 then no_chocolate=1;

else if gap>=30 then no_chocolate+1;

run;

Bear in mind that if you want to count exclusively the days between to dates you need to adjust by subtracting one day:

For example, if date_received=17-may-2015 and date_finished=16-may-2015, former minus the latter would return 1 day, is that the expected result? maybe you are looking for something like this:

gap=date_received-lag(date_finished)-1;

Hope it helps.

Daniel Santos @ www.cgd.pt;

[div44]

The finished date for Twix is what I was looking for which is 18May, and it is here that the code collapses

[Kurt_Bremser]

Run my code. If it doesn't do what you want, post the modified example data step, and where the result differs from your expectations.

[Jagadishkatam]

please try the sql code,

data have;
infile cards missover;
input Person	Chocolate$	Date_Received:date9.	Date_Finished:date9.;
format date: date9.;
cards;
1	Snickers	7-May-15	11-May-15	
1	MM	        8-May-15	13-May-15	
1	Twix	    10-May-15	18-May-15	
1	Bounty	    12-May-15	16-May-15	
1	Hersheys	17-Jun-15	21-Jun-15	
;

proc sql;
create table test as select a.*, b.Date_Received as other_rec, b.Date_Finished as other_fini,a.Date_Received-b.Date_Finished as day, b.Chocolate as choc from have as a, 
(select Chocolate,person, Date_Received, Date_Finished from have) as b where a.person=b.person;
quit;

[Kurt_Bremser · Accepted solution]

data have;
infile cards missover;
input Person	Chocolate$	Date_Received:date9.	Date_Finished:date9.;
format date: date9.;
cards;
1 Snickers 7-May-15 11-May-15
1 MM 8-May-15 13-May-15
1 Twix 10-May-15 18-May-15
1 Bounty 12-May-15 16-May-15
1 Hersheys 17-Jun-15 21-Jun-15
1 Milka 31-aug-15 05-sep-15
;
run;

data want;
set have;
by person;
retain max_finish;
no_chocolate = 0;
if not first.person
then do;
  if date_received - max_finish > 30
  then no_chocolate = 1;
end;
max_finish = max(max_finish,date_finished);
run;

I added an additional data line to make sure that a value of 1 for no_chocolate is triggered.