topic Re: Getting the first observation by group in SAS Programming

Getting the first observation by group

rashmirao99 — Fri, 14 Dec 2018 17:35:05 GMT

Hi,

I have a lab dataset where I want to take the first observation for each category for each visit and subject. This is how it looks:

usubjid parameter visit

1001 chemistry screening

1001 Hematology screening

1001 urinalysis screening

1001 chemistry Day1

1001 hematology Day1

1001 urinalysis Day1

this is how data look like and have several subjects and another two visits. But the pattern is same.

The desired data is:

1001 chemistry screening

1001 hematology screening

1001 urinalysis screening

1001 chemistry day1

1001 hematology day1

1001 urinalysis day1.

Can someone please help with the code?

Thanks

Rashmi.

Re: Getting the first observation by group

VDD — Fri, 14 Dec 2018 17:44:39 GMT

your question references columns not in your dataset.

@rashmirao99 wrote

I have a lab dataset where I want to take the first observation for each category for each visit and subject. This is how it looks:

is the category referencing the parameter and the subject referencing the usubjid?

Re: Getting the first observation by group

PeterClemmensen — Fri, 14 Dec 2018 17:44:46 GMT

So you want to do this for all the variables, correct? You basically want to remove duplicates?

Re: Getting the first observation by group

Jagadishkatam — Fri, 14 Dec 2018 17:46:18 GMT

proc sort data=lab out=want nodupkey;
by usubjid parameter visit;
run;

Re: Getting the first observation by group

novinosrin — Fri, 14 Dec 2018 18:04:49 GMT

data have;
input (usubjid              parameter            visit) (:$12.);
cards;
1001                 chemistry            screening
1001                 chemistry            screening
1001                 chemistry            screening
1001                 chemistry            screening
1001                 Hematology         screening
1001                 Hematology         screening
1001                 Hematology         screening
1001                  urinalysis            screening
1001                  urinalysis            screening
1001                  urinalysis            screening
1001                  chemistry            Day1
1001                  chemistry            Day1
1001                  chemistry            Day1
1001                  hematology         Day1
1001                  hematology         Day1
1001                  urinalysis             Day1
;
data want;
set have;
by usubjid visit  parameter notsorted;
if first.parameter;
run;