Hello, I need to find the number of repeat visits within a year, starting from the initial visit. Ex., data is as below. A has 0 repeat visits within a year, B has 6, C has 1. I tried the LAG and INTCK functions, but couldn't get the correct answer.
ID | TIME_IN |
A | 5/8/2015 |
A | 10/25/2016 |
B | 6/3/2016 |
B | 7/6/2016 |
B | 8/22/2016 |
B | 10/31/2016 |
B | 1/9/2017 |
B | 2/24/2017 |
B | 4/7/2017 |
C | 7/7/2014 |
C | 7/29/2014 |
C | 8/24/2015 |
C | 10/28/2015 |
C | 1/4/2016 |
Here's a simple way:
data want;
set have;
by id;
if first.id then do;
repeat_visits=0;
baseline_date = time_in;
end;
else if time_in <= baseline_date + 365 then repeat_visits + 1;
if last.id;
retain baseline_date;
keep id baseline_date repeat_visits;
run;
There are fancier ways (other than adding 365) to define "within a year" including ways that account for leap years. So it depends on how exact you want to be.
And what defines a repeat visit? Post test data in the form of a datastep and show what you want to have output. Then explain the logic of why. As for your problem, simply:
data want; set have; retain repeat; by id; if first.id then repeat=0; else repeat=repeat+1; run;
I'm not sure I follow your logic? How does B have 6 repeat visits? What is the exact definition for a repeat visit?
Here's a simple way:
data want;
set have;
by id;
if first.id then do;
repeat_visits=0;
baseline_date = time_in;
end;
else if time_in <= baseline_date + 365 then repeat_visits + 1;
if last.id;
retain baseline_date;
keep id baseline_date repeat_visits;
run;
There are fancier ways (other than adding 365) to define "within a year" including ways that account for leap years. So it depends on how exact you want to be.
Hi,
there are several ways to perform.
I have 4 in mind:
- use the classic retain
- use proc SQL update
- use call execute
- use the new function dosubl for a more straight forward approach which blows my mind 🙂
I've described the retain and dosubl in the code below:
data test;
informat ID $1. TIME_IN mmddyy10.;
input id time_in;
format TIME_IN mmddyy10.;
datalines;
A 5/8/2015
A 10/25/2016
B 6/3/2016
B 7/6/2016
B 8/22/2016
B 10/31/2016
B 1/9/2017
B 2/24/2017
B 4/7/2017
C 7/7/2014
C 7/29/2014
C 8/24/2015
C 10/28/2015
C 1/4/2016
;
run;
/* RETAIN approach */
data test1;
set test;
by id time_in;
retain min max h_repeatVisits .;
if first.id then do;
min=intnx("day", time_in, 1, "sameday");
max=intnx("year", time_in, 1, "sameday");
h_repeatVisits=0;
end;
if min<time_in<=max then h_repeatVisits=h_repeatVisits+1;
run;
proc sort data=test1; by id descending time_in;run;
data test2;
set test1;
by id descending time_in;
retain repeatVisits .;
if first.id then repeatVisits=h_repeatVisits;
drop min max h_repeatVisits;
run;
proc sort data=test2; by id time_in; run;
/* DOSUBL approach */
data test3;
set test;
by id time_in;
retain repeatVisits 0;
if first.id then do;
rc=dosubl('%LET n=0;
PROC SQL noprint;
SELECT count(*) INTO :n
FROM test
WHERE id EQ "'||strip(id)||'"
AND '||put(time_in,best8.)||'<time_in<= '||put(intnx("year", time_in, 1, "sameday"),best8.)
||';QUIT;');
repeatVisits=input(symget('n'),best8.);
end;
drop rc;
run;
- Cheers -
Thank you for the various methods and increasing my knowledge ... I really appreciate it !!
Count the occurrence of year within each ID and subtract 1?
proc summary data=have nway; class id date; format date year4.; output out=yearcount (drop=_type_); run;
will have a variable _freq_ with the count.
Assumes that your date is a SAS date value and NOT a character variable.
A data step could subtract the 1.
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