KEEP Statement
- KEEP variable-list;
The KEEP statement specifies which
variables in the data file are to be included in the OUT= data set.
Only the time series and event variables can be specified
in a KEEP statement.
All the BY variables and the time ID variable DATE are always
included in the OUT= data set; they cannot be referenced in
a KEEP statement.
If they are referenced, a warning message is given and the reference
is ignored.
The variable list can contain variable names
or name range specifications.
See the section "Variable Lists" for details.
There is a default KEEP list for each file type. Usually, descriptor
type variables, like footnotes, are not included in the default KEEP
list. If you give a KEEP statement, the default list becomes
undefined.
Only one KEEP or one DROP statement can be used.
KEEP and DROP are mutually exclusive.
You can also use the KEEP= data set option
to control which variables to include in the OUT= data set.
However, the KEEP statement differs from the KEEP= data set option in
several aspects:
- The KEEP statement selection is applied
before variables are read from the data file,
while the KEEP= data set option selection is applied
after variables are read and as they are written to the OUT= data set.
Therefore, using the KEEP statement instead of the KEEP= data set option
is much more efficient.
- If the KEEP statement causes no series variables to be selected, then
no observations are output to the OUT= data set.
- The KEEP statement variable specifications are applied to each cross
section independently. This behavior may produce different
variables than those produced by the KEEP= data set option when
order-range variable list specifications are used.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
