#Python's usage of regular expressions
In Python, regular expressions are used via the re module. Since regular expressions have their own escape syntax, it’s common to use Python raw strings to avoid double escaping.
| Function | Description | Example |
|---|---|---|
| match | Checks if the string matches the pattern from the beginning | See below |
| search | Searches for a substring matching the pattern | See below |
| sub | Replaces substrings that match the pattern | See below |
| split | Splits string using substrings that match the pattern | See below |
| compile | Compiles a pattern for reuse | See below |
#Pattern Matching
import re
# Validate email format
email_pattern = r'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$'
if re.match(email_pattern, "[email protected]"):
print("Valid email")
#Text Search
import re
text = "Order ID: 12345, Date: 2023-08-15"
match = re.search(r'Order ID: (\d+), Date: (\d{4}-\d{2}-\d{2})', text)
if match:
print(0, match.group(0))
print(1, match.group(1))
print(2, match.group(2))
#Text Replacement
import re
text = "Username: user Password: 123456"
hidden = re.sub(r'\d{6}', '******', text)
print(hidden)
#Text Splitting
import re
data = "Apple, Banana, Orange, Grape"
fruits = re.split(r',\s*', data) # Split by comma, allowing optional space after
print(fruits) # Output: ['Apple', 'Banana', 'Orange', 'Grape']
#Compiling Regular Expressions
Compiling a pattern improves efficiency when used multiple times.
import re
# Compile email pattern
email_pattern = re.compile(r'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$')
if email_pattern.match("[email protected]"):
print("Valid email")