Introduction to Regular Expressions in Python
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Contents
Introduction
Regular expressions are sequences of characters that form a search pattern, mainly used for string searching and manipulation. In Python, they are implemented through the built-in 're' module.
Basic Concepts
- Patterns: Specific sequences of characters that represent a search criteria.
- Metacharacters: Special characters that signify broader types of patterns (like '*', '+', '?').
- Character Classes: Represent a set of characters that match any one character from the set (like '\d', '\w', '\s').
Use Cases
- String Parsing: Extracting specific information from text.
- Data Validation: Ensuring formats of data are correct (like emails, phone numbers, passwords).
- Text Preprocessing: Used in natural language processing for tasks like tokenization, cleaning data.
Regular expressions` patterns
Special characters:
. - any charachter, except newline (\n)
^ - start of the string or line
$ - end of the string
\* - the previous charachter repeats 0 or more times =={0,}
\+ - the previous charachter repeats 1 or more times =={1,}
? - the presence of the previous charachter is not necessary =={0,1}
{n, m} - the previous charachter repeats from n till m times
{n} - the previous charachter repeats exactly n times
