Scribd is the worlds largest social reading and publishing site. Onepass macro processor a onepass macro processor that alternate between macro definition and macro expansion in a recursive way is able to handle recursive macro definition. Sometimes you forget a semicolon, a or a or a %mend. Then it processes the global statements, data steps and proc steps, as you would expect in any sas program which did not have macro code in it. Macros and macro processors free download as powerpoint presentation. Understanding and using the macro facility tree level 1. How the macro processor compiles a macro definition tree level 3. Introduction to sas macro language 6 triggering the macro processor.
The macro facility is an important feature of the sas. To illustrate how the compiler and the macro processor work together, the following figure contains the macro processor and the macro variable symbol table. The syntax is simple, and sas procedures are usually tuned to do a good job of processing the data efficiently. Using the sas macro language to create portable programs. However, they are not required for most macro programming. Sas macros for faster data manipulation complete tutorial. Replacing text strings using macro variables on page 4 explains how to create a macro.
Macro processor algorithm andmacro processor algorithm and data structuresdata structures because of the onepass structure, the definition of a macro must appear in the source ppg yrogram before any statements that invoke that macro three main data structures involved in anthree main data structures involved in an onepass macro processor. Macros from beginning to mend a simple and practical approach to the sas macro facility michael g. How a macro program is compiled 114 how a macro program executes 120. I know of a string that sometimes works and resets the macro processor. Makro prozessor, %str, %nrstr, %quote, %nrquote, %bquote, %nrbquote, % su. The %par sas macro is designed to answer questions such as this by estimating the pop. Data and set cannot be used for raw data and infile and input cannot be used for existing sas. I work with unix sas and my version of sas doesnt have access to html output because of some network issues.
I want to create a pdf output and for each of the above frequency tables and store it either in a single pdf or in a multiple pdf snot too particular on that. You then expand the macro using sas inputoutput functions to allocate a sas library and read various items from the descriptor portions of the data sets in that. The sas macro facility is a tool which lends flexibility to your sas code and promotes easier maintenance. But, while macros certainly can be challenging, it is also true that the basic concepts are not difficult to learn. The macro facility is a text processing facility for automating and customizing. A macro consists of a name, a set of formal parameters and a body of code. The macro processor translates the macro syntax into standard sas syntax which is then compiled.
These concepts are helpful in understanding how the macro processor works with other parts of the sas system. In additonal, there is a decided advantage to being able to calculate values outside of a data step, because adding another. Sas simulations simulation is a computational technique that uses repeating computation on many different random samples in order to estimate a statistical quantity. Using macros to automate sas processing sas support. When sas compiles program text, two delimiters trigger macro processor activity. This section introduces the sas macro facility using simple examples and explanation. Some functions of the sas macro processor are to pass symbolic values between sas statements and steps. Two delimiters will trigger the macro processor in a sas program. Restriction the definition of a macro must appear in the source program before any statements that invoke that macro.
We sometimes need a way to interact with the macro facility during data step execution. Sas code you will learn the syntax, to detect number of variables in a dataset create loop to run for all the variables of a dataset detect number of distinct categories for all variables pass a. A sas program is a combination of data steps, global statements, sas component language scl, sql statements and sas macro statements. Syntax description %sysevalfexpression troubleshooting macro variable references enables you to write your own messages to the sas log. I use the terms preprocessing and macro processing, or. To create a sas data set from raw data, you use infile and input statements. Sas macro language also gives you the opportunity to insert programming steps inside a sas code. Dec 05, 2019 how sas processes statements with macro activity. Using normal sas functions in macro processing some of the magic in advanced macro processing comes from the ability to use normal sas functions, sometimes referred to as data step functions. Sas data set can be created using another sas data set as input or raw data to create a sas data set using another sas data set, the data and set statements are used. This paper is designed for people who know the basics of sas programming, but know nothing about sas macro programming. The macro processor creates an entry in the symbol table for the macro variable year.
Just beneath our eyes lies an incredible world of bizarre looking creatures, vibrant colors. Sql processing to a macro variable, especially summary statistics. A sas macro is way of defining parts of or collections of sas statements which can be carried out repeatedly or which can substitute names of datasets or variables with symbolic names. When a keyword is found, it is replaced by some text. Macro quoting functions mask special characters and mnemonic operators so that the macro processor interprets them as text instead of elements of the macro language. Implement by processing for your entire sas program the sas.
For sas programmers or analysts who need to generalize their programs or improve programming efficiency, art carpenter thoroughly updates his highly successful second edition of carpenters complete guide to the sas macro language with an extensive collection of new macro language techniques and examples. A macro is a unit of specification for program generation through expansion. They are provided so that you can understand what is going on behind the. Macros and macro processors macro computer science. In a program with macro activity, the macro processor can generate text that is placed on the input stack to be tokenized by the word scanner. What is a sas macro n how to define n use sas macro start. This refers to a macro, which may generate a section of a statement, one or more complete. The sas par macro ellen hertzmark, handan wand, and donna spiegelman march 8, 2012 abstract what % of the cases would be prevented if it were possible to eliminate one or more risk factors from a target population. Thus, the macro language serves as a dynamic editor for sas programs. Dec 05, 2019 how the macro processor compiles a macro definition tree level 3. In the fastpaced world in which we live, its easy to lose sight of the immense beauty which surrounds us. Node 3 of 5 node 3 of 5 how the macro processor executes a compiled macro tree level 3.
In simple terms, when macros are used within a sas program, the control is passed over to the macro processor, which in turn. Cohen astrazeneca lp abstract the sas macro language is another language that rests on top of regular sas code. Mar 20, 2012 most sas procedures support the by statement, which allows you to create a report or analysis for each distinct value of a variable in your data set. Twopass macro processor would not allow the body of one macro instruction to contain definitions of other macros. This chapter describes a typical pattern that the sas system follows to process a program. The example in this section shows you how the macro processor creates and resolves a macro variable.
Introduction to sas programming university libraries. Other features of the macro language 10 getting started with the macro facility this is the macro facility language reference for sas. Since data in a sas data set is accessed at execution time, this means that we do not have sas data available to create a macro variable when using the %let statement. The macro processor evaluates the %let statement, creates a macro variable named teenager, and stores y as its value in the macro symbol. How the macro processor compiles a macro definition. We explain how the macro processor works, and how to. If the program does not contain any macro statements, then processing continues as normal with the data or proc step processor. The following table lists the macro quoting functions, and also describes the special characters that they mask and when they operate. However, not every program is improved by using macros.
The pre processor reads through the whole program, one or more times, converting macro code into text strings. All macro invocation statements are expanded during the second pass. Basic macro processor functions macro invocation often referred to as a macro call need the name of the macro instruction begin invoked and the arguments to be used in expanding the macro expanded program figure 5. Macro processing introduction defining and calling macros how the macro processor compiles a macro definition. A second sas programming language for string manipulation. Before sas can compile and execute your program, sas must pass your macro statements to the macro processor which then resolves your macros generating. A generalpurpose macro processor or general purpose preprocessor is a macro processor that is not tied to or integrated with a particular language or piece of software a macro processor is a program that copies a stream of text from one place to another, making a systematic set of replacements as it does so. Page 1 sas macro programming tips, tricks and techniques kirk paul lafler, software intelligence corporation, spring valley, california abstract the sas macro language is a powerful feature for extending the capabilities of the sas system. If implmac is in effect and you have defined a statementstyle macro in your program, the macro processor scans the first word of every sas statement to see whether it is a statementstyle macro invocation. When sas is going to compile a sas program it first sends the program to a word scanner which intercepts the macro syntax before it can reach the compiler. A macro processor is a program that reads a file or files and scans them for certain keywords. Sas macro programming tips and techniques south central sas.
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