How to write a Python regular expression to use re.findall()?

This article will explain how to write a Python regular expression to use re.findall() method. Regular expression, or regex, is used in searching and extracting patterns in text. Python provides the re module to work with regex, and re.findall() to find all matches of a pattern in a string.

The re.findall() method returns a list of all occurrences of a pattern. It works with strings for extracting data and supports metacharacters for pattern matching.

There are various ways to use the re.findall() method in Python, such as ?

• Find One or More Digits
• Find All Words in a String
• Extract Email Addresses
• Find Dates in a Text

Syntax

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

Parameters:

• pattern ? The regular expression pattern to search for
• string ? The input string to search in
• flags ? Optional flags to modify pattern behavior

Find One or More Digits

The following example uses r"\d+" to find one or more digits, as '\d' represents digits. The re.findall() method will extract all matching parts and return a list of found numbers ?

# Import regular expressions module
import re

# Define a string to search
text = "abc 123 xyz 456"

# Use a regular expression 
pattern = r"\d+"

# Find all matches of the pattern in the text
matches = re.findall(pattern, text)

# Print the matches found
print(matches)  

The output of the above code is ?

['123', '456']

Find All Words in a String

In this example, we use the r"\w+" pattern to find all the words present in the given string. The regex \w+ matches one or more word characters (letters, digits, underscores) ?

# Import regular expressions module
import re

# Define a string to search
text = "Hello world, welcome to Python!"

# Use a regular expression to find all words in the string
pattern = r"\w+"

# Find all matches of the pattern in the string
matches = re.findall(pattern, text)

# Print the result
print(matches)

The output of the above code is ?

['Hello', 'world', 'welcome', 'to', 'Python']

Extract Email Addresses

In the following example, we use \b[\w.%+-]+@[\w.-]+\.\w+\b regex pattern to capture all email addresses. The re.findall() method will search and extract email patterns from the given text ?

# Import regular expressions module
import re

# Define a string to search
text = "Email me at example@tutorialspoint.com or contact@tutorix.com"

# Define a pattern to match email addresses
pattern = r"\b[\w.%+-]+@[\w.-]+\.\w+\b"

# Use re.findall to find all occurrences of the pattern in the string
matches = re.findall(pattern, text)

# Print the result
print(matches) 

The output of the above code is ?

['example@tutorialspoint.com', 'contact@tutorix.com']

Find Dates in a Text

Here, our pattern to find dates is \b\d{2,4}[-/]\d{2}[-/]\d{2,4}\b. This program will find dates written with different separators like - or / ?

# Import regular expressions module
import re

# Define a string with dates to search
text = "My important dates are: 26-05-2024, 27/06/2025, 2023-07-28"

# Define a pattern to match dates in various formats
pattern = r"\b\d{2,4}[-/]\d{2}[-/]\d{2,4}\b"

# Find all matches of the pattern in the text
matches = re.findall(pattern, text)

# Print the results
print(matches) 

The output of the above code is ?

['26-05-2024', '27/06/2025', '2023-07-28']

Common Regex Patterns

Conclusion

The re.findall() method is powerful for extracting patterns from text using regular expressions. Use specific patterns like \d+ for digits, \w+ for words, and complex patterns for emails or dates to extract structured data efficiently.