SAS Data Set Options

IN= Data Set Option

Creates a Boolean variable that indicates whether the data set contributed data to the current observation.

Valid in:	DATA step
Category:	Observation Control
Restriction:	Use with the SET, MERGE, MODIFY, and UPDATE statements only.

Syntax
Syntax Description
Details
Examples
See Also

Syntax

IN=variable

Syntax Description

variable: names the new variable whose value indicates whether that input data set contributed data to the current observation. Within the DATA step, the value of the variable is 1 if the data set contributed to the current observation, and 0 otherwise.

Details

Specify the IN= data set option in parentheses after a SAS data set name in the SET, MERGE, MODIFY, and UPDATE statements only. Values of IN= variables are available to program statements during the DATA step, but the variables are not included in the SAS data set that is being created, unless they are assigned to a new variable.

When you use IN= with BY-group processing, and when a data set contributes an observation for the current BY group, the IN= value is 1. The value remains as long as that BY group is still being processed and the value is not reset by programming logic.

Examples

In this example, IN= creates a new variable, OVERSEAS, that denotes international flights. The variable I has a value of 1 when the observation is read from the NONUSA data set. Otherwise, it has a value of 0. The IF-THEN statement checks the value of I to determine whether the data set NONUSA contributed data to the current observation. If I=1, the variable OVERSEAS receives an asterisk (*) as a value.

data allflts;
   set usa nonusa(in=i);
   by fltnum;
   if i then overseas='*';
run;