SAS 9.4 Language Reference, 6th Edition

number-of-elements

is the number of variables in the group. You must enclose this value in either

parentheses (), braces {}, or brackets [].

$

specifies that the elements in the array are character elements.

length

specifies the length of the elements in the array that have not been previously

assigned a length.

array-elements

is a list of the names of the variables in the group. All variables that are defined in a

given array must be of the same type, either all character or all numeric.

initial-value-list

is a list of the initial values for the corresponding elements in the array.

For complete information, see the “ARRAY Statement” in SAS DATA Step Statements:

Reference.

To reference an array that was previously defined in the same DATA step, use an Array

Reference statement. An array reference has the following form:

array-name {subscript}

where

array-name

is the name of an array that was previously defined with an ARRAY statement in the

same DATA step.

subscript

specifies the subscript, which can be a numeric constant, the name of a variable

whose value is the number, a SAS numeric expression, or an asterisk (*).

Note: Subscripts in SAS are 1-based by default, and not 0-based as they are in some

other programming languages.

For complete information, see the Array Reference statement in the SAS DATA Step

Statements: Reference.

Processing Simple Arrays

Grouping Variables in a Simple Array

The following ARRAY statement creates an array named Books that contains the three

variables Reference, Usage, and Introduction:

array books{3} Reference Usage Introduction;

When you define an array, SAS assigns each array element an array reference with the

form array-name{subscript}, where subscript is the position of the variable in the list.

The following table lists the array reference assignments for the previous ARRAY

statement:

568 Chapter 25 • Array Processing

Table 25.1 Array Reference Assignments for Array Books

Variable Array Reference

Reference books{1}

Usage books{2}

Introduction books{3}

Later in the DATA step, when you want to process the variables in the array, you can

refer to a variable by either its name or its array reference. For example, the names

Reference and Books{1} are equivalent.

Using a DO Loop to Repeat an Action

To perform the same action several times, use an iterative DO loop. A simple iterative

DO loop that processes an array has the following form:

DO index-variable=1 TO number-of-elements-in-array;

… more SAS statements …

END;

The loop is processed repeatedly (iterates) according to the instructions in the iterative

DO statement. The iterative DO statement contains an index-variable whose name you

specify and whose value changes at each iteration of the loop.

To execute the loop as many times as there are variables in the array, specify that the

values of index-variable are 1 TO number-of-elements-in-array. SAS increases the value

of index-variable by 1 before each new iteration of the loop. When the value exceeds the

number-of-elements-in-array, SAS stops processing the loop. By default, SAS

automatically includes index-variable in the output data set. Use a DROP statement or

the DROP= data set option to prevent the index variable from being written to your

output data set.

An iterative DO loop that executes three times and has an index variable named count

has the following form:

do count=1 to 3;

… more SAS statements …

end;

The first time that the loop processes, the value of count is 1; the second time, 2; and the

third time, 3. At the beginning of the fourth iteration, the value of count is 4, which

exceeds the specified range and causes SAS to stop processing the loop.

Using a DO Loop to Process Selected Elements in an Array

To process particular elements of an array, specify those elements as the range of the

iterative DO statement. For example, the following statement creates an array Days that

contains seven elements:

array days{7} D1-D7;

The following DO statements process selected elements of the array Days:

Processing Simple Arrays 569