http://brown.edu/go/regexWelcome to Regular Expressions. We will begin at 4:00 While you’re waiting, please ● download this presentation at

http://brown.edu/go/regex● download and (if you can) print off

the RegEx cheatsheet at https://tinyurl.com/ovz8pao

https://tinyurl.com/ovz8pao

http://brown.edu/go/regex

Regular ExpressionsSearch and Replace with Advanced Pattern MatchingPatrick Rashleigh

http://brown.edu/go/regex

First things first● Download this presentation at

http://brown.edu/go/regex● Download this RegEx

cheatsheet● Open up chat in Zoom● Mute the mic in Zoom

http://brown.edu/go/regexhttp://web.mit.edu/hackl/www/lab/turkshop/slides/regex-cheatsheet.pdfhttp://web.mit.edu/hackl/www/lab/turkshop/slides/regex-cheatsheet.pdf

http://brown.edu/go/regex

IntroductionsBriefly introduce yourself in the chat (any of this is optional)● name● area of study● what brings you to a Regular

Expressions workshop?

http://brown.edu/go/regex

Workshop format● I talk a bit, demo via screen sharing;

you post questions to chat● You do a challenge for a few minutes

while I check the chat for questions● Post your solutions to chat; discuss● Repeat!

http://brown.edu/go/regex

What is a Regular Expression?

http://brown.edu/go/regex

A text pattern matching language that is used in many tools

http://brown.edu/go/regex

b*t matches beet and bot and bat

http://brown.edu/go/regex

“Show me all the names of characters in Pride and Prejudice mentioned in other characters’ speech”

http://brown.edu/go/regexExample of Data Mining Free Text

http://regex101.com/r/sS3vM6/2

http://brown.edu/go/regex

Behold: the Regular Expression language!

"[^"]*M(s|rs?)\.(\s+[A-Z]\w+)+[^"]*"

http://brown.edu/go/regexExample of data cleaning structured text

http://regex101.com/r/nN4fE3/2

http://brown.edu/go/regex

Text editors

(in this case, Sublime Text)

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Data cleaners

(in this case, Open Refine)

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Programming languagesPython, Javascript, SQL, R, and pretty much any language

http://brown.edu/go/regex

Our tool today:RegEx101.com

http://brown.edu/go/regex

Take a deep breath and let’s go step by stepStep 1:Basic matching

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LiteralsDemo

http://regex101.com/r/iI9dA0/2

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Symbols\d \w \s \nDemo

http://regex101.com/r/pR6xE0/2

http://brown.edu/go/regexCHALLENGELinkFind all Rhode Island telephone numbers (401 area code)Post your solution to the chat

http://regex101.com/r/pR6xE0/2

http://brown.edu/go/regex

Step 2:Character classes

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List: [...]Not-list: [^...]Ranges: [A-Z]Disjunction: ( | )Demo

http://regex101.com/r/iI9dA0/2

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Boundary: \bMatching a condition, not a characterDemo

http://regex101.com/r/iI9dA0/2

http://brown.edu/go/regexCHALLENGELinkMatch all 4-letter words beginning with f (any case). Don't use the i flagPost your solution to the chat

http://regex101.com/r/iI9dA0/2

http://brown.edu/go/regex

Step 3:Quantifiers

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0 or more Xs1 or more XsX may existBetween m and n Xs

X*X+X?X{m,n}

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Only affects the immediately previous entity (character or group)Demo

http://regex101.com/r/iI9dA0/2

http://brown.edu/go/regexCHALLENGELinkMatch all words of any length that start with a capital letterPost your solution to the chat

http://regex101.com/r/iI9dA0/2

http://brown.edu/go/regexCHALLENGE 2LinkGet the text of all quotes (i.e. falling between quotation marks)Post your solution to the chat

https://regex101.com/r/sS3vM6/1

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You now have all the knowledge to read this!

"[^"]*M(s|rs?)\.(\s+[A-Z]\w+)+[^"]*"

(and if it’s still gobbledygook, you know where to find me to follow up)

http://brown.edu/go/regex

Thank youpatrick_rashleigh@brown.eduWorkshop feedback formenter “Regex” for the workshop title

http://brown.edu/go/workshop-evaluation