topic Re: check dates in SAS Procedures

check dates

sam369 — Mon, 17 Aug 2015 17:25:06 GMT

Hi All,

i need to check the date with previous visit in the group. i have visits up to 50, and different from each group. below is how data look like

Have:

data have;

input sub grp vis dt;

cards;

100 xxx v1 20jun2012

100 xxx v2 27aug2012

100 xxx v3 15sep2012

100 xxx v4 20aug2012

100 yyy v1 20jun2012

100 yyy v2

100 yyy v3 15sep2012

100 yyy v4 15sep2012

100 zzz v1 20jun2012

100 zzz v2 27aug2012

100 zzz v3 10mar2012

100 zzz v3 15sep2012

100 aaa v1 20jun2012

100 aaa v2 27aug2011

100 aaa v3 15sep2012

100 aaa v4 25dec2012

100 bbb v1 20jun2013

100 bbb v2 27aug2012

100 bbb v3 15sep2012

want:

isub grp vis dt

flg;

100 xxx v1	20jun2012
100 xxx v2	27aug2012
100 xxx v3	15sep2012
100 xxx v4	20aug2012	1
100 yyy v1	20jun2012

100 yyy v2

100 yyy v3	15sep2012
100 yyy v4	15sep2012
100 zzz v1	20jun2012
100 zzz v2	27aug2012
100 zzz v3	10mar2012	1
100 zzz v3	15sep2012
100 aaa v1	20jun2012
100 aaa v2	27aug2011	1
100 aaa v3	15sep2012
100 aaa v4	25dec2012
100 bbb v1	20jun2013	1
100 bbb v2	27aug2012	1
100 bbb v3	15sep2012	1

Thanks

Sam

Re: check dates

ballardw — Mon, 17 Aug 2015 17:47:55 GMT

What is the rule for flagging? It looks like for some that the flag is when the date is earlier than the previous but you have

100 bbb v1

20jun2013

which is the first visit, so does not match that rule.

Also, are your dates currently SAS date values or character?

Re: check dates

sam369 — Mon, 17 Aug 2015 18:26:02 GMT

Hi Ballardw,

Dates are in character format. yes you are right, the subject doesn't have flg

sub grp vis dt flg

100 bbb v1

20jun2013

The rule for the flg is, to check the dates with previous dates in that grp. if the visit date is after the previous visit date i need to flg them .

Thanks

Sam

Re: check dates

ChrisNZ — Tue, 18 Aug 2015 00:03:39 GMT

Use a read-ahead technique. For eg

data WANT;

merge HAVE

HAVE(firstobs=2

keep =SUB GRP DT

rename =(SUB=NEXT_SUB GRP=NEXT_GRP DT=NEXT_DT)) ;

if SUB=NEXT_SUB & GRP=NEXT_GRP & DT>NEXT_DT then FLG=1;

drop NEXT:;

run;

Re: check dates

Astounding — Tue, 18 Aug 2015 00:37:01 GMT

You'll have to verify that your solution works properly when a date is missing. That being said, here's an approach:

data want;

set have;

by sub vis;

if first.sub then prior_dt = input(dt, date9.);

else if dt > ' ' then do;

if input(dt, date9.) < prior_dt then flag=1;

else prior_dt = input(dt, date9.);

end;

retain prior_dt;

run;

It's untested, but you can give it a try.

Good luck.

Re: check dates

Kurt_Bremser — Tue, 18 Aug 2015 07:10:27 GMT

(convert dt to a SAS date variable before processing)

data want (drop=olddate);

set have;

by grp notsorted;

retain olddate;

if first.grp then olddate = .;

if olddate > dt then flg = 1;

if dt ne . then olddate = dt;

run;

Re: check dates

ChrisNZ — Tue, 18 Aug 2015 08:52:47 GMT

The flag must be set on the preceding record in the example given.

Re: check dates

RW9 — Tue, 18 Aug 2015 08:59:39 GMT

Hi,

I would also have date as numeric, and visit as numeric - have a look at CDISC standards, Visit and Visitnumber. If you have them in the correct format then sort by date and if visitnum ne lag(visitnum)+1 then error.

Re: check dates

Kurt_Bremser — Tue, 18 Aug 2015 09:14:30 GMT

As I see it, the flag needs to be set on the succeeding record with the earlier date.

While testing, I found I needed to do a slight correction, so now the code is:

data want (drop=olddate);

set have;

by grp notsorted;

retain olddate;

if first.grp then olddate = .;

if olddate > dt and dt ne . then flg = 1;

if dt ne . then olddate = dt;

run;

Re: check dates

sam369 — Tue, 18 Aug 2015 14:32:31 GMT

Thank you All

Sam