I came across a lot of beginners begin as macro programmers than using SAS language. I wonder why that happens.
@Tomcaty Please follow the rules when you contemplating using macro language--? Below is some excerpt from my publishing at my college, maybe useful for you
1. Base SAS Programming Skills Example: Data step processing that includes PDV (program data vector), implicit loop that comprises Implicit Output. Implicit return etc:
2. Extensive knowledge of SAS functions and dataset options for Data manipulation A SAS function performs a computation or system manipulation on arguments and returns a value. In base SAS software, you can use SAS functions in DATA step programming statements, in macro language statements, and in Structured Query Language (SQL) Example using max, sqrt, min functions:
data _null_; x=max(cash,credit); x=sqrt(1500); NewCity=left(upcase(City)); x=min(YearTemperature-July,YearTemperature-Dec); s=repeat(’----+’,16); x=min((enroll-drop),(enroll-fail)); put x= s= ; run;
3. SAS Statements, keywords and Global Options :
4. Understanding data structures and mechanism of reading and writing external files.
5. Minimizing the number of programming lines marking less resource usage Example:
6. Proper use of formatted code for better readability helps in case of any future edits.
7. Choosing the right statement for conditional processing. For example, IF and Where Example:
8. Choosing either to program the code in a Datastep or Proc SQL by determining which is more efficient and serves best for a particular query. Example:
9. Knowledge in using different Proc’s effectively will help accomplishing faster execution of programs as opposed to Datastep execution.
10. Disk vs in memory processing
11. Familiarity of short cuts such as Arrays and iterative processing will result in speedy execution and minimize of the number of lines in writing a SAS program.
Importance of incorporating best practices using SAS Macro facility
First off, macro language is layer on top of sas language
Step1: Write an automated and debug a SAS program without macro coding
Step2: Generalize the program by replacing hardcoded values with macro variable references
Step3: Create a macro definition with macro parameters.
Step4: Add macro level programming for conditional and iterative processing.
Step5: Data driven customization. Data driven customization means flexibility of a macro execution using parameter validation that is data driven.
It is assumed SAS folks are highly proficient in the above 5 steps and considering that I would not go into the details of what’s a macro facility, a macro program or a SAS program flow and related concepts such as tokenization, compilation and execution.
For those who think they are slightly unfamiliar I would recommend comprehensive reading on parameterization- Positional keyword and mixed, macro storage, temporary and permanent catalog, creating macro variables in the Datastep and in SQL using macro functions and call and indirect references.
The common SAS Macro best practices I have encountered or experienced so far are as follows-
1. Choice of Positional vs. Keyword vs. Mixed Parameters
2. Choosing Local vs. Global Macro Variables
3. Suffixing a macro variable reference with a period (.).
4. Challenge of defining macros within a macro Nesting macro definitions inside other macros is usually unnecessary and inefficient. When you call a macro that contains a nested macro definition, the macro processor generates the nested macro definition as text and places it on the input stack. The word scanner then scans the definition and the macro processor compiles it. If you nest the definition of a macro that does not change, you cause the macro processor to compile the same macro each time that section of the outer macro is executed. Example: /* Nesting a Macro Definition--INEFFICIENT */ %macro stats1(product,year);
5. Conditional processing using % do loops and %if for conditional execution with focus on saving compile time.
