Essential SAS Functions: SUBSTR, SCAN, STRIP, CEIL & FLOOR
Master core string slicing, token extraction, and numeric rounding operations in DATA steps.
📌 Direct Answer / Executive Definition
SAS built-in character and numeric functions perform row-level data transformations. Key string functions include SUBSTR (extracting substrings by character position), SCAN (extracting words by delimiter), and STRIP (removing leading and trailing blanks). Key numeric functions include CEIL, FLOOR, INT, and ROUND for precision handling.
Why Robust String Slicing & Discretization Matter for Data Cleaning
Data cleaning and standardization in real-world pipelines require precise text slicing, phone/code parsing, and numeric discretization before feeding statistical procedures.
Standard Syntax, Derivation & Framework Pattern
/* String Parsing & Numeric Discretization */
DATA work.cleaned_records;
SET work.raw_feed;
/* Extract 3-letter site prefix and visit number */
Site_Code = SUBSTR(Patient_Ref, 1, 3);
Visit_Num = INPUT(SCAN(Patient_Ref, 2, '-'), 8.);
/* Clean leading/trailing spaces */
Full_Name = STRIP(First_Name) || ' ' || STRIP(Last_Name);
/* Numeric rounding & truncation */
Dose_Ceil = CEIL(Raw_Dose); /* Smallest integer >= value */
Dose_Floor = FLOOR(Raw_Dose); /* Largest integer <= value */
RUN;Core Rules & Certification Takeaways
- SUBSTR(string, start, length) extracts fixed-width characters starting at a 1-based index.
- SCAN(string, n, delimiter) extracts the nth word delimited by specified characters regardless of position.
- STRIP removes both leading and trailing whitespace, while TRIM removes only trailing spaces.
- CEIL rounds up to the next integer; FLOOR rounds down; ROUND rounds to specified decimal precision.
🔗 Related Architectural Concepts & Next Steps
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Frequently Asked Questions (FAQ)
What is the difference between SUBSTR and SCAN in SAS?
SUBSTR extracts characters based on exact starting position and length, whereas SCAN extracts words/tokens based on delimiter characters.
How does STRIP differ from TRIM in SAS?
TRIM removes only trailing blanks, whereas STRIP removes both leading and trailing whitespace from the string.
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