SAS : Count Distinct Values of Variables

proc sql;
create table t as
select count(distinct make) as n_make, count(distinct type) as n_type
,count(distinct origin) as n_origin
from sashelp.cars;
quit;

PROC FREQ : Count Distinct Values

ods output nlevels = charlevels;
proc freq data=sashelp.cars (keep = make type origin) nlevels;
tables make type origin / nopercent nocol nocum nofreq noprint;
run;
ods output close;

Performance Testing : PROC SQL vs. PROC FREQ

I have stacked raw data set multiple times (500 to 5000 times) to check the performance of these two procedures. In addition, i have added NOPRINT and ODS OUTPUT CLOSE to improve efficiency of the PROC FREQ code.

Count Distinct Values of a Variable

%macro stack (inputdata = sashelp.cars, iterations=, out=);

data temp;

length x $45.;

do i = 1 to &iterations.;

if i then x = "&inputdata.";

output;

end;

drop i;

run;

proc sql noprint;

select x into: n separated by ''

from temp;

quit;

data &out.;

set &n;

run;

ods output nlevels = charlevels;

proc freq data=outdata (keep = make type origin) nlevels;

tables make type origin / nopercent nocol nocum nofreq noprint;

run;

ods output close;

proc sql;

create table t as

select count(distinct make) as n_make, count(distinct type) as n_type

,count(distinct origin) as n_origin

from outdata;

quit;

%mend;

%stack (inputdata = sashelp.cars, iterations= 500, out= outdata);

%stack (inputdata = sashelp.cars, iterations= 1000, out= outdata);

%stack (inputdata = sashelp.cars, iterations= 2000, out= outdata);

%stack (inputdata = sashelp.cars, iterations= 5000, out= outdata);