first and last date/time constraints

[monday89]

Hi I have the following dataset. What I would like to do is FIRST instance and LAST INSTANCE per patient, I would like the duration to be the same. But for the middle, i would like to set up duration = 24. 

patientID	time	first_date_time	stop_date_time	duration	weight
111	1	1/2/2020 1:20	1/2/2020 23:59	22	24
111	2	1/3/2020 0:00	1/3/2020 21:23	21	24
111	3	1/4/2020 2:00	1/4/2020 18:18	16	24
222	1	2/1/2020 9:20	2/1/2020 23:59	14	19
222	2	2/2/2020 0:00	2/2/2020 19:12	19	19
222	3	2/3/2020 3:00	2/3/2020 20:23	17	19
222	3	2/4/2020 1:00	2/4/2020 23:23	22	19

This:

patientID	time	first_date_time	stop_date_time	duration	weight	duration_final
111	1	1/2/2020 1:20	1/2/2020 23:59	22	24	22
111	2	1/3/2020 0:00	1/3/2020 21:23	21	24	24
111	3	1/4/2020 2:00	1/4/2020 18:18	16	24	24
222	1	2/1/2020 9:20	2/1/2020 23:59	14	19	14
222	2	2/2/2020 0:00	2/2/2020 19:12	19	19	24
222	3	2/3/2020 3:00	2/3/2020 20:23	17	19	24
222	3	2/4/2020 1:00	2/4/2020 23:23	22	19	22

It didnt work:

data want; set have;

   by PatientID time;

   if first. time then  do;   duration_final = duration  end;

   else  if last. time then   do;  duration_final = duration end;

   else  do;  duration_final = 24 end;

run;

[sustagens]

I would do the first. and last. indicators on patient ID instead of time.

data want;
set have;
by patientID time;
if first.patientid or last.patientid then duration_final=duration;
else duration_final=24;
run;

Also I would only do; and end; if I am performing multiple "then"s, in your case because you are only doing one "then" scenario, I don't see a need for it. KISS 🙂

[kelxxx]

Hello,

It doesn't work because you forgot to put semicolons following the instructions (before end) and it must change

first.patient_id /last.patient_id instead of first.time / last.time

P/s: the loop "do...end" is not necessary if there is only one instruction. i think "by time" is not necessary too.

Have a nice day.

[andreas_lds]

Why is duration_final = 24 for the last observation with patientID = 111? This does not match the description.

The log should contain syntax-errors for the lines 3-5 of your data-step. @kelxxx already explained the reason: a semicolon is required before "end;".

Keeping do...end-blocks is highly recommended, properly formatted those blocks increase readability and help avoiding common mistakes, when adding another statement that should be executed conditionally.