REGEX
Regular Expressions
What are regular Expressions?
A way of describing patterns within search strings
validating Emails
colt@gmail.com
carly.simon@yahoo.com
(^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$)
rosa-98@meals.org
david+lee+roth@hotmail.com
shoe_queen91@hello.net
Let's use a regular expression!
Starts with 1 or more letter,number,+,_,-,. then
A single @ sign then
1 or more letter, number, or - then
A single dot then
ends with 1 or more letter, number,-, or .
Potential Use Cases
- Credit Card number validating
- Phone number validating
- Advanced find/replace in text
- Formatting text/output
- Syntax highlighting
def hello_world(thingy):
#I do nothing
print("Hello World!")First,
let's start with
REGEX outside of Python
There are a ton of regex symbols.
I'm just going to cover some important ones
SOME REGEX SYNTAX
| \d | digit 0-9 |
| \w | letter, digit, or underscore |
| \s | whitespace character |
| \D | not a digit |
| \W | not a word character |
| \S | not a whitespace character |
| . | any character except line break |
Some Characters
SOME REGEX SYNTAX
| + | One or more |
| {3} | Exactly x times. {3} - 3 times |
| {3,5} | Three to five times |
| {4,} | Four or more times |
| * | Zero or more times |
| ? | Once or none (optional) |
Quantifers
SOME REGEX SYNTAX
| ^ | Start of string or line |
| $ | End of string or line |
| \b | Word boundary |
Anchors and Boundaries
LOGICAL OR
| (pipe character)
"Mr|Mrs|Ms"
I could make 20+ slides on Regex syntax.
It's easier to look at a cheat sheet
NOW,
Let's Move on TO
USING REGEX WITH PYTHON
Using Regex in Python
#import regex module
import re
#define our phone number regex
pattern = re.compile(r'\d{3} \d{3}-\d{4}')
#search a string with our regex
res = pattern.search('Call me at 415 555-4242!')REGEX
By colt
REGEX
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