SORT Procedure

KEY Statement

Specifies sorting keys and variables. The KEY statement is an alternative to the BY statement. The KEY statement syntax allows for the future possibility of specifying different collation options for each KEY variable. Currently, the only options allowed are ASCENDING and DESCENDING.

Restriction:	The BY statement cannot be used with the KEY statement.
Tip:	Multiple KEY statements can be specified.

Syntax

Required Argument

Optional Arguments

Syntax

KEY variable(s) </ option> ;

Required Argument

variable(s)

specifies the variable by which PROC SORT orders the observations. Multiple variables can be specified. Each of these variables must be separated by a space. A range of variables can also be specified. For example, the following code shows how to specify multiple variables and a range of variables:

 data sortKeys;
    input x1 x2 x3 x4 ;
 cards;
    7 8 9 8
    0 0 0 0
    1 2 3 4 ;
 run;
 proc sort data=sortKeys out=sortedOutput;
    key x1 x2-x4;
 run;

Multiple KEY statements can also be specified. The first sort key encountered from among all sort keys is considered the primary sort key. Sorting continues for every specified KEY statement and its variables. For example, the following code shows how to specify multiple KEY statements:

 proc sort data=sortKeys out=sortedOutput;
    key x2;
    key x3;
 run;

The following code example uses the BY statement to accomplish the same type of sort as the previous example:

 proc sort data=sortKeys out=sortedOutput;
    by x2 x3;
 run;

Optional Arguments

ASCENDING

sorts in ascending order the variable or variables that it follows. Observations are sorted from the smallest value to the largest value. The ASCENDING keyword modifies all the variables that precede it in the KEY statement.

Alias:ASC

Default:ASCENDING is the default sort order.

Tip:In a PROC SORT KEY statement, the ASCENDING option modifies all the variables that it follows. The option must follow the /. In the following example, the x1 variable in the input data set is sorted in ascending order.

 proc sort data=sortVar out=sortedOutput;
    key x1 / ascending;
 run;

DESCENDING

reverses the sort order for the variable that it follows in the statement so that observations are sorted from the largest value to the smallest value. The DESCENDING keyword modifies all the variables that it precedes in the KEY statement.

Alias:DESC

Default:ASCENDING (ASC) is the default sort order.

Tip:In a PROC SORT KEY statement, the DESCENDING option modifies the variables that follows it. The option must follow the /. In the following example, the x1 and x2 variables in the input data set is sorted in descending order:

 proc sort data=sortVar out=sortedOutput;
    key x1 x2 / descending;
 run;

The following example uses the BY statement to accomplish the same type of sort as the previous example:

 proc sort data=sortVar out=sortedOutput;
    by descending x1 descending x2 ;
 run;