How to Master the regex in Python: A simple way to use regex to perform finding, replacing, splitting, or validating text

nqvinhtong
Python regex

A regular expression, or regex, is a sequence of characters that defines a search pattern for strings. You can use regexes in Python to perform various tasks, such as finding, replacing, splitting, or validating text. Python has a built-in module called re that provides various functions and methods to work with regexes.

To use regexes in Python, you need to import the re module and create a regex object using the re.compile () function. The regex object has several methods that allow you to apply the regex pattern to a string and get the matching results. For example, you can use the match () method to check if the string matches the pattern from the beginning, or the search () method to check if the string contains the pattern anywhere. You can also use the findall () method to get a list of all matches, or the sub () method to replace the matches with another string.

Here is an example of how to use regexes in Python to find and replace email addresses in a text:

# Import the re module
import re

# Define the text
text = "My email is corgicode88@example.com and yours is nqvinhtong@example.com"

# Define the regex pattern for email addresses
pattern = r"\w+@\w+\.\w+"

# Create a regex object
regex = re.compile(pattern)

# Find all matches in the text
matches = regex.findall(text)
print(matches) # ['corgicode88@example.com', 'nqvinhtong@example.com']

# Replace all matches with a new string
new_text = regex.sub("hidden", text)
print(new_text) # My email is hidden and yours is hidden

An other example, the following code will search for the pattern “Corgi” in the string “Hello, Corgi!”:

import re

string = "Hello, Corgi!"
pattern = re.compile("Corgi")

match = pattern.search(string)

if match:
  print("The Corgi was found in the string.")
else:
  print("The Corgi was not found in the string.")

Output

The Corgi was found in the string.

Regular expressions can be used to solve a wide variety of problems in Python. For example, you can use them to:

  • Validate user input.
  • Extract data from text.
  • Search for and replace text in a document.
  • Perform text mining tasks.

Regular expressions can be a powerful tool for working with text and data in Python. However, they can also be complex to learn and use. If you are new to regular expressions, I recommend starting with a tutorial or resource such as the Python documentation.

https://docs.python.org/3/howto/regex.html

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