Creating new variables

[OJohn_StaT]

Hello ,

I am trying to create a new variable for days between just the first visit and the second visit in each year. Also I am trying to create another variable for number of visit for each year. Could you please help me for this issue because I am struggling. Here is a sample of the dataset. Thank you for your time and your help in advance.

data Member_Data_Sample;
input VISIT_DATE :date9. MEMBER_ID $ VISIT_YEAR VISIT_STATUS;
format  VISIT_DATE :date9.;
datalines;
06NOV2013 AA10450Z 2013 0 
05JUN2014 AA10450Z 2014 1 
26JUN2014 AA10450Z 2014 1 
21AUG2014 AA10450Z 2014 1 
18SEP2014 AA10450Z 2014 1 
03DEC2014 AA10450Z 2014 1 
11MAR2015 AA10450Z 2015 1 
15APR2015 AA10450Z 2015 1 
07OCT2015 AA10450Z 2015 1 
13OCT2015 AA10450Z 2015 1 
26OCT2015 AA10450Z 2015 1 
09NOV2015 AA10450Z 2015 1 
07DEC2015 AA10450Z 2015 1 
21DEC2015 AA10450Z 2015 1 
19APR2017 AA10450Z 2017 1 
10SEP2018 AA10450Z 2018 0 
15APR2019 AA10450Z 2019 1 
;
run;

data Member_Data_Sample;
input VISIT_DATE :date9. MEMBER_ID $ VISIT_YEAR VISIT_STATUS;
format VISIT_DATE :date9.;
datalines;
06NOV2013 AA10450Z 2013 0
05JUN2014 AA10450Z 2014 1
26JUN2014 AA10450Z 2014 1
21AUG2014 AA10450Z 2014 1
18SEP2014 AA10450Z 2014 1
03DEC2014 AA10450Z 2014 1
11MAR2015 AA10450Z 2015 1
15APR2015 AA10450Z 2015 1
07OCT2015 AA10450Z 2015 1
13OCT2015 AA10450Z 2015 1
26OCT2015 AA10450Z 2015 1
09NOV2015 AA10450Z 2015 1
07DEC2015 AA10450Z 2015 1
21DEC2015 AA10450Z 2015 1
19APR2017 AA10450Z 2017 1
10SEP2018 AA10450Z 2018 0
15APR2019 AA10450Z 2019 1
;
run;

[PaigeMiller · Accepted solution]

data want;
    set member_data_sample;
    by member_id visit_year;
    delta_days=visit_date-lag(visit_date);
    if first.visit_year then do;
        delta_days=.;
        counter=0;
    end;
    counter+1;
run;