Data Manipulation in SAS

Reading and Filtering Data

• Create a copy of data using DATA output-table; SET input-table; RUN;
• Filter rows using WHERE expression in a DATA step. Example: DATA output-table; SET input-table; WHERE age > 25; RUN;
• Specify columns in the output using DROP or KEEP. Example: DROP col1 col2; or KEEP col3 col4;

Formatting Columns

• Format columns in a DATA step using FORMAT. Example: FORMAT col-name format;

Computing New Columns

• Create new columns using expressions. Example new-column = expression;
• SAS automatically assigns type and length to new columns. Character columns' length is based on the assigned string length.
• Character strings must be quoted and are case-sensitive.

Using Functions

• Calculate summary statistics using functions (e.g., SUM, MEAN, MIN, MAX, N). Exclude missing values by default.
• Character functions like UPCASE, LOWCASE, PROPCASE are available.
• Date functions extract parts of dates (e.g., MONTH, YEAR, DAY).
• CATS concatenates strings.
• SUBSTR extracts substrings.
• MDY creates a date from month, day, year values.
• TODAY returns the current date as a SAS date.
• Use functions within expressions, like, new-column = function(arguments);

Conditional Processing

• Use IF-THEN statements for simple conditions. Example: IF age > 65 THEN DO; statement; END;
• Use IF-THEN-ELSE for more complex conditions. Example: IF age > 65 THEN DO; expensive; END; ELSE DO; cheap END;
• Use IF-THEN-DO for multiple statements based on a condition. Example: IF score > 90 THEN DO; print 'Excellent'; grade = 'A'; END;