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Python Regular Expressions in Python Introduction to Regular Expressions Sets

vikas pal
vikas pal
11,252 Points
Posted by vikas pal
vikas pal
11,252 Points

explain sets in python

please explain me briefly about sets for example in the video he said that [aple] matches 'apple' .how it match apple. i tried to find apple match in a file which i created names.txt.i typed apple in last of the line but it doesn't match it .it matched the starting p and said it matches p.here is the all thing of script

import re
name=open('names.txt')
data=name.read()
name.close()
first_name=r'Vikas'
last_name=r'pal'
#print(re.match(first_name,data))
#print(re.search(last_name,data))
#print(re.findall(r'\(?\d{3}\)?-?\s?\d{3}-\d{4}',data))
#print(re.findall(r'\w*, \w+',data))
#print(re.findall(r'[\w\d+.]+@[-\w\d+.]+',data))
print(re.search(r'[aple]',data))

and names.txt

pal, Vikas vikaspal@gmail.com (555) 555-5555 student, school, @vikas_enjoy
pal, Divya divya@gmail.com (666) 555-5554 student, college, @divya_pal
pal, Pratibha pratibha@gmail.com (444) 555-5552 student, secondary, @pratibha pal
love, kennneth kenneth@teamtreehouse.com (555) 555-5543 teacher, treehouse @kennethlove
McFarland, dave dave@teamtreehouse.com (555) 555-5553 teacher, treehouse 
Arthur, king king_artur@camelot.co.uk  king, camelot
Osterberg, sven-Erik governor@norrbotten.co.se Governor, Norrbotten @sverik
, Tim tim@killerrabbit.com Enchanter, killer Rabbit Cave
carson,Ryan ryan@teamtreehouse.com (555) 555-5534 CEO, treehouse @ryancarson
Docter, The docter+companion@tardis.co.uk   Time Lord, Gallifrey
Exampleson, Example me@example.com 555-555-5553 Example Co. @example
Obama, Barack president.44@us.gov 555 555-5551 President, United States of America @potus44
Chalkley, Andrew andrew@teamtreehouse.com (555) 555-4444 Sith Lord, Galactic Empire @darthvader
apple

1 Answer

Kenneth Love
STAFF
Kenneth Love
Treehouse Guest Teacher
Kenneth Love
Kenneth Love
Treehouse Guest Teacher

A regex set is a collection of things that can be matched. The word "apple" has 4 letters in it, "a", "p", "l", and "e". The "p" is repeated, but a repetition isn't a new letter. So the set to match the characters in the word "apple" would be [aple]. Or [pale]. Or [ealp]. The order isn't important, only the contents of the set.

Now this won't match the exact string "apple". It's just matching whether or not the characters appear. To match exactly "apple", you should search for exactly "apple". re.search(r"apple") instead of re.search(r"[aple]+").

Also, your search in your example isn't using the +. I don't remember if that's been covered in the course at this point or not, but that will let you match 1 or more characters in a row, not just a single character.

vikas pal
vikas pal
11,252 Points
vikas pal
vikas pal
11,252 Points

thank you so much .You cleared my all doubt about set.very helpful to me.again thanks