1. SET statement in DATA step
Based on S. David Riba’s
The Set statement and beyond:
Uses and Abuses of the SET statement

2. Simple SET statement *Simple Set statement; data temp1b; set temp1;
run;
*Concatenate;
data temp1x3;
set temp1 temp1 temp1;
*Interleave;
data temp12a;
set temp1 temp2;by i;
*Combine;
data temp12b;
set temp2;
*Attach first observation of temp1 to all observations of temp2;
data temp12c;
if (_n_ eq 1) then set temp1;

3. Data set options Inside SET statement
/*Data step options in SET Statement
DROP = varlist
KEEP = varlist
FIRSTOBS = num
IN = var
OBS = num
RENAME = varlist
WHERE = condition */
*Combine data with itself to calculate change in a variables' value;
data temp3;
set temp1 ( keep = x ) ;
set temp1 ( firstobs = 2 rename = ( x=frwx ) );
delta = x-frwx;
run;
*The IN = data set option is used with multiple data sets where it is important to know which data set contributed an observation;
data temp4 ;
set temp1 ( in = in_1 )
temp2 ( in = in_2 ) ;by i;
if ( in_1 ) then x2=x**2 ;
else if ( in_2 ) then yexp=exp(y);
DATA temp5 ;
Set temp1 ( where = ( x>.5 ) )
temp2 ( where = ( y<.5 ) ) ;

4. SET statement options /*SET statement OPTIONS END = var KEY = index
NOBS = var
POINT = var */
*END statement;
*The END = option is used to identify the last observation processed by a SET statement.;
data temp6;
set temp1 end = eof ;
set temp2;
if ( eof ) then do ;
lx=x;
ly=y;
end;
run;

5. can be either a simple key or a composite key;
*KEY statement;
*The KEY = option retrieves observations from an indexed data set based on the index key, which
can be either a simple key or a composite key;
data pan1;
do i=1 to 30;
k=i;
x=rand('unif');
output;
end;
run;
data pan2(index=(k));
do i=1 to 20;
k=i+10;
y=rand('unif');
data pan3 ;
set pan1;
set pan2 key = k;
xymax=max(x,y);

6. *NOBS statement;
*The NOBS = option creates a variable which contains the total number of observations
in the input data set(s). If multiple data sets are listed in the SET statement, the value in
the NOBS = variable are the total number of observations in all the listed data sets.;
*use a data set if nobs is what you want;
data temp7;
if (0) then set temp1 ( drop=_ALL_ ) temp2 ( drop=_ALL_ ) nobs=totobs;
if ( totobs ) then set temp1 temp2;
else abort ;
run;
*just figure out the nobs of your data set;
data _null_;
call symput( 'n_obs' , put ( n_obs, 5. ) ) ;
stop;
set temp1 temp2 nobs = n_obs;
%put &n_obs;

7. *POINT statement; *The POINT = option uses a numeric variable for direct (or random) access into a SAS data set. The value of the POINT = variable must be specified before it can be used.; *use the third observation; data temp8; ptr = 3; set temp1 point = ptr ; if ( _error_ ) then abort ; output; stop; run; *reverse the order of your data; data temp9; do ptr = lastrec to 1 by -1 ; set temp1 point = ptr nobs = lastrec ; end;

8. *Random replicates of data set; data john1; do i = 1 to 20; x=rand('unif'); output; end; run; data john2; do _i_ = 1 to 10; ptr = ceil ( totobs * ranuni ( totobs ) ) ; set john1 point = ptr nobs = totobs ; if ( _error_ ) then abort ; stop;

9. *Replicates of observations;
data kevin1;
do i=1 to 10;
start=1;
stop=i;
output;
end;
run;
data kevin2;
x=rand('unif');
data kevin3;
set kevin1;
do ptr = start to stop ;
set kevin2 point = ptr ;
if ( _error_ ) then abort ;

10. *Input Min, Max, Sum etc. in your data set; data voytek; retain minval maxval sumval ; if ( _N_ eq 1 ) then do until (lastrec) ; set temp1 (keep = x) end = lastrec; minval = min ( minval, x ) ; maxval = max ( maxval, x ) ; sumval = sum ( sumval, x ) ; end; set temp1 ; run;