Introduction to Regular Expressions in SAS [Windham 2014-11-18].pdf

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Introduction to
Regular Expressions
in SAS
®
K. Matthew Windham
support.sas.com/bookstore
The correct bibliographic citation for this manual is as follows: Windham, K. Matthew. 2014.
Introduction to
Regular Expressions in SAS
®
. Cary, NC: SAS Institute Inc.
Introduction to Regular Expressions in SAS
®
Copyright © 2014, SAS Institute Inc., Cary, NC, USA
ISBN 978-1-61290-904-2 (Hardcopy)
ISBN 978-1-62959-498-9 (EPUB)
ISBN 978-1-62959-499-6 (MOBI)
ISBN 978-1-62959-500-9 (PDF)
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Contents
About This Book ........................................................................................ vii
About The Author ...................................................................................... xi
Acknowledgments .................................................................................... xiii
Chapter 1: Introduction .............................................................................. 1
1.1 Purpose of This Book .............................................................................................................. 1
1.2 Layout of This Book ................................................................................................................. 1
1.3 Defining Regular Expressions................................................................................................. 2
1.4 Motivational Examples ............................................................................................................ 3
1.4.1 Extract, Transform, and Load (ETL) .............................................................................. 3
1.4.2 Data Manipulation .......................................................................................................... 4
1.4.3 Data Enrichment ............................................................................................................. 5
Chapter 2: Getting Started with Regular Expressions ................................. 9
2.1 Introduction ............................................................................................................................ 10
2.1.1 RegEx Test Code .......................................................................................................... 11
2.2 Special Characters ................................................................................................................. 13
2.3 Basic Metacharacters ............................................................................................................ 15
2.3.1 Wildcard ......................................................................................................................... 15
2.3.2 Word ............................................................................................................................... 15
2.3.3 Non-word ....................................................................................................................... 16
2.3.4 Tab.................................................................................................................................. 16
2.3.5 Whitespace .................................................................................................................... 17
2.3.6 Non-whitespace ............................................................................................................ 17
2.3.7 Digit ................................................................................................................................ 17
2.3.8 Non-digit ........................................................................................................................ 18
2.3.9 Newline .......................................................................................................................... 18
2.3.10 Bell ............................................................................................................................... 19
iv
2.3.11 Control Character ....................................................................................................... 20
2.3.12 Octal ............................................................................................................................. 20
2.3.13 Hexadecimal................................................................................................................ 21
2.4 Character Classes .................................................................................................................. 21
2.4.1 List .................................................................................................................................. 21
2.4.2 Not List........................................................................................................................... 22
2.4.3 Range ............................................................................................................................. 22
2.5 Modifiers ................................................................................................................................. 23
2.5.1 Case Modifiers .............................................................................................................. 23
2.5.2 Repetition Modifiers ..................................................................................................... 25
2.6 Options .................................................................................................................................... 32
2.6.1 Ignore Case ................................................................................................................... 32
2.6.2 Single Line ..................................................................................................................... 32
2.6.3 Multiline ......................................................................................................................... 33
2.6.4 Compile Once................................................................................................................ 33
2.6.5 Substitution Operator................................................................................................... 34
2.7 Zero-width Metacharacters .................................................................................................. 34
2.7.1 Start of Line ................................................................................................................... 35
2.7.2 End of Line..................................................................................................................... 35
2.7.3 Word Boundary ............................................................................................................. 35
2.7.4 Non-word Boundary ..................................................................................................... 36
2.7.5 String Start .................................................................................................................... 36
2.8 Summary ................................................................................................................................. 37
Chapter 3: Using Regular Expressions in SAS ........................................... 39
3.1 Introduction ............................................................................................................................ 39
3.1.1 Capture Buffer............................................................................................................... 39
3.2 Built-in SAS Functions ........................................................................................................... 40
3.2.1 PRXPARSE .................................................................................................................... 40
3.2.2 PRXMATCH ................................................................................................................... 42
3.2.3 PRXCHANGE ................................................................................................................. 43
3.2.4 PRXPOSN ...................................................................................................................... 46
3.2.5 PRXPAREN .................................................................................................................... 47
v
3.3 Built-in SAS Call Routines ..................................................................................................... 49
3.3.1 CALL PRXCHANGE ...................................................................................................... 50
3.3.2 CALL PRXPOSN ............................................................................................................ 54
3.3.3 CALL PRXSUBSTR ....................................................................................................... 56
3.3.4 CALL PRXNEXT ............................................................................................................ 57
3.3.5 CALL PRXDEBUG ......................................................................................................... 59
3.3.6 CALL PRXFREE............................................................................................................. 62
3.4 Summary ................................................................................................................................. 63
Chapter 4: Applications of Regular Expressions in SAS ............................ 65
4.1 Introduction ............................................................................................................................ 65
4.1.1 Random PII Generator ................................................................................................. 66
4.2 Data Cleansing and Standardization.................................................................................... 72
4.3 Information Extraction ........................................................................................................... 77
4.4 Search and Replacement ...................................................................................................... 80
4.5 Summary ................................................................................................................................. 83
4.5.1 Start Small ..................................................................................................................... 83
4.5.2 Think Big ........................................................................................................................ 83
Appendix A: Perl Version Notes ................................................................ 85
Appendix B: ASCII Code Lookup Tables .................................................... 87
Non-Printing Characters ............................................................................................................. 87
Printing Characters ...................................................................................................................... 89
Appendix C: POSIX Metacharacters .......................................................... 97
Index ...................................................................................................... 101

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