subtract a date variable only if the next date is not a certain length

gsk — Fri, 13 Mar 2020 16:15:30 GMT

student seq date1 date2

'1' 1      2017-11-11   2017-11-18
'1'    2    2017-11-18T14:57 2018-02-14
'1'    3    2018-02-14 2018-02-28

'1' 4 2018-02-28 2018-03-14

'2' 1 2018-02-14 2018-02-28

'2' 2 2018-02-28T09:18 2018-03-14

all the variables are categorical. how do we subtract 1 from the date2 only if the next record of date1 doesn't have time components attached to it? Resulting data should be:

subj seq date1 date2

'1' 1 2017-11-11 2017-11-18
'1' 2 2017-11-18T14:57 2018-02-13
'1' 3 2018-02-14 2018-02-27

'1' 4 2018-02-28 2018-03-14

'2' 1 2018-02-14 2018-02-28

'2' 2 2018-02-28T09:18 2018-03-14

I tried to create a sas dataset but that gave invalid sas variable error.. So the below code doesn't work, but if this can help:

data test ;
input student $ seq date1 $ date2 $ ;
datalines;
1 1 2017-11-11 2017-11-18
1 2 2017-11-18T14:57 2018-02-14
1 3 2018-02-14 2018-02-28
1 4 2018-02-28 2018-03-14
2 1 2018-02-14 2018-02-28
2 2 2018-02-28T09:18 2018-03-14
;

Re: subtract a date variable only if the next date is not a certain length

gsk — Fri, 13 Mar 2020 16:13:20 GMT

What I tried so far: first, sort

proc sort data=test out=test1;
by subjid seq;
run;

data test2;
set test1;
by subjid seq;
if length(date2) >= 10 and not last.subjid then do; *<-by the way, both dates can contain time components;
date2_n= input(date2, yymmdd10.)-1;
date2_c= strip(put(date2_n, yymmdd10.)); *<- I need a character version of the new date later;
end;
run;

But this subtracts all not last dates even though the next date1 has time component

topic subtract a date variable only if the next date is not a certain length in SAS Programming

subtract a date variable only if the next date is not a certain length

Re: subtract a date variable only if the next date is not a certain length