Selecting Variables (1)

Reading and Concatenating SAS Data Sets

Selecting Variables

When you create a new data set, you can use options to drop or keep variables that are stored in the original data set. You name the variables that you want to drop or keep using the DROP= and KEEP= data set options.

You can use the KEEP= option instead of the DROP= option if more variables are dropped than kept. You specify data set options in parentheses after a SAS data set name.

General form, DROP= and KEEP= data set options:
(DROP=variable-1 < . . . variable-n>)
(KEEP=variable-1 < . . . variable-n>)

where

the DROP= or KEEP= option, in parentheses, follows the name of the data set containing the variables to be dropped or kept
variable is the name of one or more variables, separated by blanks.

Because you are only interested in treadmill time and tolerance levels, for example, you may want to drop the variables ID, Name, RestHR, MaxHR, and RecHR and keep the variables TimeMin, TimeSec, and Tolerance when you create the TestTime data set.

     data work.testtime(keep=timemin timesec tolerance);
        set clinic.stress2(drop=id name
            resthr maxhr rechr);
        if placebo='YES';
     run;

SAS Data Set Stress2 (Partial Listing)

ID	Name	RestHR	MaxHR	RecHR	TimeMin	TimeSec	Tolerance
2458	Murray, W	72	185	182	12	38	D
2462	Almers, C	68	171	133	10	5	I
2501	Bonaventure, T	78	177	139	11	13	I
2523	Johnson, R	69	162	114	9	42	S