1 SAS #SASGF ® GLOBAL FORUM 2020 Paper 4419-2020 A Beginner’s Guide to Using ARRAYs and DO Loops Jennifer L. Waller, Augusta University, Augusta, GA ABSTRACT If you are copying and pasting code over and over to perform the same operation on Because these macros are self-contained and use global macro variables, you can use them freely in “open code”. The macros use regular characters as much The names must be either variables that you define in the ARRAY statement or variables that SAS creates by concatenating the array name and a number. This blog discusses an immensely useful technique that allows you to perform an operation on all numeric or all character variables in a SAS data set. SAS doesn't support that syntax directly, but there is a variant of the DO loop in which you can iterate over values in a specified list. First, let’s walkthrough the different components of a SAS array. Because these macros are self-contained and use global macro variables, you can use them freely in “open code”. You will often see SAS programmers use the dim function in a Do Loop because it lets them iterate over each element in an array.. Dim and Range. The outer DO loop (DO I=1 TO 2) processes the inner DO loop twice. Example 3 - Using DO OVER to Simplify your DO Loops with Arrays To alleviate the need for manual counting of array elements, SAS also provides the DO OVER loop option to work with non-indexed arrays. To create a temporary array, use the _TEMPORARY_ argument. The most commonly used array type is the explicit SAS Array, which can be broken down into 6 main components: array array-name {X} $ length array-elements initial-values The actions of some DO loops are unconditional in that if you tell SAS to do something 20 times, SAS will do it 20 times regardless. The names must be either variables that you define in the ARRAY statement or variables that SAS creates by concatenating the array name and a number. Temporary array elements are automatically retained, instead of being reset to missing at the beginning of the next iteration of the DATA step. The syntax in the DATA step is to specify a list of values (numeric or character) after the equal sign. When programming, you can find yourself needing to tell SAS to execute the same statements over and over again. For example, when the subscript is a number (not the asterisk), you do not need to name each variable in the array. For each iteration of the DO loops, SAS substitutes the value of the array element corresponding to the current values of I and J. A SAS array name is just one way to reference a group of variables that you want to have treated as though it was like an array. The inner DO loop (DO J=1 TO 5) applies the ROUND function to all the variables in one row. As you start building larger arrays with more and more variables, non-indexed arrays can be a helpful tool. The Dim Function is quite simple. The macros use regular characters as much as possible, For example, when the subscript is a number (not the asterisk), you do not need to name each variable in the array. Next, let us look at the Dim and Range Functions. For a complete guide on SAS DO LOOPs, see The Complete Guide to Do-loop, Do-while and Do-Until found here. So anytime you use the reference BONDS, SAS will expect you to use a subscript or index, such as BONDS(1) (which points to X1) or BONDS(2) (which points to X2). That's when a DO loop can come in and save your day. and %DO_OVER macros are analogous to the ARRAY and DO OVER statements in the SAS data step language, which define and loop over implicitly subscripted arrays. Although they behave like variables, temporary array elements do not have names, and they do not appear in the output data set. 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