Download - The Bastards Book of Regular Expressions

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Specific and limited repetitionThe plus operator is a nice catch-all for repeated patterns. But as you can imagine, sometimes you’llneed to match something that is repeated more than once but less than infinity.Curly bracesTo capture n repetitions of a pattern – where n is the number of repetitions – enclose n inside curlybracesThe following pattern:a{4}– will match exactly four a characters:"B**aaaa**", said the sheepThis is the simplest form of the curly braces notation, let’s practice using it before learning the otherforms.Exercise: zeros to millionsIn the following list of numbers:100200050000040000002000000100000080009000000Replace the zeroes with millions for the numbers that have exactly six zeroes:49
Specific and limited repetition 5010020005000004 million2 million1 million80009 millionAnswerFind 0{6}Replace millionBonus exercisePerform the same exercise as above, but with this list of numbers:90080000009000000070000100000000200000050000000000If you use the exact solution as in the prior example, you’ll end up with this:9008 million9 million0700001 million002 million5 million0000Oops. That pattern matched and replaced the first six zeroes. What we need is to replace the lastsix zeroes:
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The Bastards Book ofRegular Express
Page 5 and 6: CONTENTSOptionality and alternation
Page 7 and 8: CONTENTSSwitching visualizations (T
Page 9 and 10: Regular Expressions are for Everyon
Page 11 and 12: Regular Expressions are for Everyon
Page 13 and 14: Getting Started6
Page 15 and 16: Finding a proper text editor 8Notep
Page 17 and 18: Finding a proper text editor 10Edit
Page 19 and 20: Finding a proper text editor 12Text
Page 21 and 22: Finding a proper text editor 14does
Page 23 and 24: Finding a proper text editor 16Yest
Page 25 and 26: Finding a proper text editor 18A do
Page 27 and 28: A better Find-and-Replace 20The lim
Page 29 and 30: A better Find-and-Replace 22Using R
Page 31 and 32: Your first regex 24helloThe Find-an
Page 33 and 34: Your first regex 26The regex syntax
Page 35 and 36: Your first regex 28Double-bounded
Page 37 and 38: Your first regex 30AnswerFind \bcat
Page 39 and 40: Removing emptinessIt’s funny how
Page 41 and 42: Removing emptiness 34Now let’s do
Page 43 and 44: Removing emptiness 36…as opposed
Page 45 and 46: Removing emptiness 38Replacement in
Page 47 and 48: Match one-or-more with the plus sig
Page 55: Match zero-or-more with the star si
Page 59 and 60: Specific and limited repetition 52E
Page 61 and 62: Specific and limited repetition 54C
Page 63 and 64: Anchors: A way to trim emptinessIn
Page 65 and 66: Anchors: A way to trim emptiness 58
Page 71 and 72: Matching any letter, any number 64A
Page 73 and 74: Matching any letter, any number 66W
Page 75 and 76: Matching any letter, any number 68[
Page 77 and 78: Matching any letter, any number 70R
Page 79 and 80: Matching any letter, any number 72F
Page 81 and 82: Matching any letter, any number 74A
Page 83 and 84: Negative character sets 76$1,200.00
Page 85 and 86: Negative character sets 78\W+Exerci
Page 87 and 88: Capture, Reuse 80Find (ba)+Matches
Page 89 and 90: Capture, Reuse 82.- then the 1st ba
Page 91 and 92: Capture, Reuse 84In English We are
Page 93 and 94: Capture, Reuse 86ApplesOraclesOrang
Page 95 and 96: Capture, Reuse 8805-14-8912-03-9803
Page 97 and 98: Capture, Reuse 90Mary asked: "What
Page 99 and 100: Optionality and alternationThe two
Page 101 and 102: Optionality and alternation 94Answe
Page 103 and 104: Optionality and alternation 96Studi
Page 105 and 106: Optionality and alternation 98You m
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Laziness and greediness 100Being to
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Laziness and greediness 102Replace
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Laziness and greediness 104With the
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Lookarounds 106cat(?=s)- will match
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Lookarounds 108`(?
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Lookarounds 110ExerciseGiven the fo
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Lookarounds 112City,CountryAlbuquer
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Lookarounds 114Given this list of c
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Lookarounds 116100,J.D. Salinger Av
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Lookarounds 1186,300|Apples|New Yor
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Lookarounds 120^(\d+) Record ID (\w
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Lookarounds 122d. Remove all asides
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From Data to HTML (TODO)This chapte
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From Data to HTML (TODO) 126Turning
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The ExercisesI’ve never been one
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Data Cleaning with the Stars 130LOR
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Data Cleaning with the Stars 132[GM
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Finding needles in haystacks (TODO)
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Changing phone format (TODO)Todo: T
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Changing phone format (TODO) 138Exe
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Changing phone format (TODO) 140Ans
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Changing phone format (TODO) 142`1-
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Changing phone format (TODO) 144(\d
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Dating, Associated Press Style (TOD
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Sorting a police blotter 154Sloppy
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Sorting a police blotter 156I used
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Converting XML to tab-delimited dat
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Converting XML to tab-delimited dat
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Cleaning up Microsoft Word HTML(TOD
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Cleaning up OCR Text (TODO)Image sc
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Moving forwardThank you for taking
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