Regular Expressions in Python - Set 2 (Search, Match and Find All)

Regular Expression in Python with Examples | Set 1
The module re provides support for regular expressions in Python. Below are main methods in this module.

Searching an occurrence of pattern 

re.search() : This method either returns None (if the pattern doesn't match), or a re.MatchObject that contains information about the matching part of the string. This method stops after the first match, so this is best suited for testing a regular expression more than extracting data.

Output : 

Match at index 14, 21
Full match: June 24
Month: June
Day: 24 

Matching a Pattern with Text 

re.match() : This function attempts to match pattern to whole string. The re.match function returns a match object on success, None on failure. 

re.match(pattern, string, flags=0)

pattern : Regular expression to be matched.
string : String where pattern is searched
flags : We can specify different flags 
 using bitwise OR (|). 

Output: 

Given Data: Jun 24
Month: Jun
Day: 24

Not a valid date

Finding all occurrences of a pattern 

re.findall() : Return all non-overlapping matches of pattern in string, as a list of strings. The string is scanned left-to-right, and matches are returned in the order found (Source : Python Docs). 

Output : 

['123456789', '987654321']

Regular expression is a vast topic. It’s a complete library. Regular expressions can do a lot of stuff. You can Match, Search, Replace, Extract a lot of data. For example, below small code is so powerful that it can extract email address from a text. So we can make our own Web Crawlers and scrappers in python with easy.Look at the below regex. 

# extract all email addresses and add them into the resulting set
new_emails = set(re.findall(r"[a-z0-9\.\-+_]+@[a-z0-9\.\-+_]+\.[a-z]+", 
 text, re.I))

We will soon be discussing more methods on regular expressions.