re.findall() in Python

re.findall() method in Python helps us find all pattern occurrences in a string. It's like searching through a sentence to find every word that matches a specific rule. We can do this using regular expressions (regex) to create the pattern and then use re.findall() to get a list of matches.

Let's say we want to find all words that start with "P" in a string.

import re

s = "Python is Powerful and Great"
result = re.findall(r'\bP\w+', s)
print(result)

['Python', 'Powerful']

Syntax of re.findall()

The syntax of re.findall() is simple:

import re

result = re.findall(pattern, string)

Parameters

• pattern: The regular expression pattern we are looking for.
• string: The string where we want to search for the pattern.
• result: This will be a list of all occurrences of the pattern in the string.

Return

The return type of re.findall() is always a list. This list contains all the non-overlapping matches of the pattern in the string. If no match is found, it will return an empty list.

Case Sensitivity in re.findall()

By default, re.findall() is case-sensitive. To make it case-insensitive, we can pass the re.IGNORECASE flag.

import re

s = "Python is fun. python is cool."
result = re.findall(r'python', s, re.IGNORECASE)
print(result)

['Python', 'python']

Finding numbers using re.findall()

Here we use a pattern that matches any number. The regular expression \d+ looks for one or more digits in a row. So if the text contains numbers like "12 apples and 5 bananas", it will find "12" and "5" and give us those as the result

import re

# Find all numbers in a string
text = "There are 12 apples, 5 bananas, and 300 oranges."

# \d+ matches one or more digits
pattern = r'\d+'  
matches = re.findall(pattern, text)
print(matches)  

['12', '5', '300']

Matching dates using re.findall()

Here we use a pattern to find dates written in the format YYYY-MM-DD. The regular expression \d{4}-\d{2}-\d{2} is designed to find a four-digit year, followed by a two-digit month and a two-digit day. If the text contains "2024-12-25" and "2025-01-15" it will pick them out as matches.

import re

#Find all dates in YYYY-MM-DD format
text = "The event is on 2024-12-25, and the deadline is 2025-01-15."

# Matches a date in YYYY-MM-DD format
pattern = r'\d{4}-\d{2}-\d{2}' 

matches = re.findall(pattern, text)
print(matches)  

['2024-12-25', '2025-01-15']