topic Re: Deleting observations in SAS Procedures

Deleting observations

jossig — Mon, 14 Feb 2011 09:58:15 GMT

Hi,

I want to keep only the four first observations for each subject in my data set. I have data which I have arranged by subjects and date, i.e. constructed as follows:

Date Subject var
17837 1 1000
17867 1 1100
17898 1 1050
17929 1 1200
17957 1 1200
17988 1 1250
18018 1 1150
17837 2 1000
17867 2 1100
17898 2 1050
17929 2 1200
17957 2 1200
17988 2 1250
18018 2 1150

What I want to do is to make a series where I keep only the first four
observations for each subject, but drop the rest. Could someone please help
me with a SAS code for such procedure?

Re: Deleting observations

Peter_C — Mon, 14 Feb 2011 10:56:45 GMT

data reduced;
do _n_=1 by 1 until( last.subject) ;
set your.data ;
by subject ;
if _n_ LE 4 then output ;
end;
run;

Re: Deleting observations

Vasile01 — Mon, 14 Feb 2011 15:19:37 GMT

Hi,

%let n=4;
data selected;
input Date Subject var;
cards;
17837 1 1000
17867 1 1100
17898 1 1050
17929 1 1200
17957 1 1200
17988 1 1250
18018 1 1150
17837 2 1000
17867 2 1100
17898 2 1050
17929 2 1200
17957 2 1200
17988 2 1250
1 3 1200
18018 2 1150
;

proc sort data=selected;
by subject date;

data selected;
set selected;
by subject date;
if first.subject then i=0;
i+1;
if i le &n then output;
drop i;
run;

A more complex example could be found at:
http://support.sas.com/kb/33/009.html

Warm regards,
Vasile

Re: Deleting observations

Ksharp — Fri, 18 Feb 2011 04:53:40 GMT

[pre]
data temp;
input Date Subject var ;
cards;
17837 1 1000
17867 1 1100
17898 1 1050
17929 1 1200
17957 1 1200
17988 1 1250
18018 1 1150
17837 2 1000
17867 2 1100
17898 2 1050
17929 2 1200
17957 2 1200
17988 2 1250
18018 2 1150
;
run;
data result;
set temp;
if subject ne lag(subject) then count=0;
count+1;
if count le 4;
run;
[/pre]

Ksharp