topic Re: Data step: setting flag on last day in SAS Programming

Data step: setting flag on last day

knveraraju91 — Sun, 06 Mar 2016 21:32:16 GMT

Hi I need help in my code.

I have three variables.

subjid seq visit

1 1 day 1

1 2 day 1

1 3 day1

1 4 day2

1 5 day2

1 6 day2

1 7 day3

1 8 day3

1 9 day3

2 1 day 1

2 2 day 1

2 3 day1

2 4 day2

2 5 day2

2 6 day2

2 7 day3

2 8 day3

2 9 day3

2 10 day4

2 11 day4

2 12 day4

i need to flag all last day visits. So I need out put like this.

subjid seq visit flag

1 1 day 1

1 2 day 1

1 3 day1

1 4 day2

1 5 day2

1 6 day2

1 7 day3 1

1 8 day3 1

1 9 day3 1

2 1 day 1

2 2 day 1

2 3 day1

2 4 day2

2 5 day2

2 6 day2

2 7 day3

2 8 day3

2 9 day3

2 10 day4 1

2 11 day4 1

2 12 day4 1

I am using the code;

proc sort data=one out=two;
by subjid seq visit ;
run;
data three;
set two;
by subjid seq visit;
if last.subjid then flag=1;
else flag='';
run;

I am getting the output like this:

subjid seq visit flag

1 1 day 1

1 2 day 1

1 3 day1

1 4 day2

1 5 day2

1 6 day2

1 7 day3

1 8 day3

1 9 day3 1

2 1 day 1

2 2 day 1

2 3 day1

2 4 day2

2 5 day2

2 6 day2

2 7 day3

2 8 day3

2 9 day3

2 10 day4

2 11 day4

2 12 day4 1

Please help in my code.

Thank you.

Re: data step

PGStats — Sun, 06 Mar 2016 02:34:39 GMT

Use two DO UNTIL blocks. The first one checks if this is the last visit. The second one writes out the whole visit. Watch for the consistency of visit names.

data one;
input subjid seq v $&;
visit = compress(v);
drop v;
datalines;
1          1     day 1
1           2     day 1
1           3      day1
1            4      day2
1            5      day2
1            6      day2
1            7      day3
1            8      day3
1            9      day3
2          1     day 1
2           2     day 1
2           3      day1
2            4      day2
2            5      day2
2            6      day2
2            7      day3
2            8      day3
2            9      day3
2            10      day4
2            11      day4
2            12      day4
;

proc sort data=one out=two;
by subjid visit seq;;
run;

data three;
do until (last.visit);
    set two; by subjId visit;
    end;
flag = last.subjId;
do until (last.visit);
    set two; by subjId visit;
    output;
    end;
run;

Re: data step

LinusH — Sun, 06 Mar 2016 10:30:35 GMT

Or do last.visit and make flag a retained variable.

Re: Data step: setting flag on last day

LinusH — Sun, 06 Mar 2016 21:32:49 GMT

Renaming the subject to better specify the question/subject.

Re: Data step: setting flag on last day

RW9 — Mon, 07 Mar 2016 10:03:00 GMT

Hi,

What do your specifcations say about last day? Your test example may work fine, but what if you have:

day 1

day 3

day 2

? Is day 2 the last day. What about unscheduled visits, repeats, data issues such as dates not matching visit name etc.? Whilst if your data is really very clean like that, then it might be ok to flag last day, I would really want some specification which details what that actually means.