• Unit 8: Regular Expressions

    At this point in the course, you should have some familiarity with applying string methods for finding a pattern within a string. Regular expressions are a syntax framework for performing more general pattern searches that allow for a measure of pattern variability. The subject of regular expressions is actually quite deep and highly relevant to the theory of computation. This unit will introduce you to the re module and its regular expression syntax to gain expertise with string pattern searches.

    Completing this unit should take you approximately 3 hours. 

    • Upon successful completion of this unit, you will be able to:

      • explain why and how regular expressions are used;
      • use regular expressions to construct search patterns to match a string or set of strings; and
      • solve common tasks by using regular expressions to match patterns.

    • 8.1: The "re" Module

      • Syntax and Usage Book

        A regular expression (or "regex") is a character sequence used to search for patterns within strings. You've already seen examples of pattern searching when we looked at strings. Regular expressions have their own syntax, which enables more general and flexible constructs to search with.

        The "re" module in Python is the tool that will be used to build regular expressions in this unit. Practice these examples to familiarize yourself with some common methods. You will also practice building more general regular expression patterns using the table of special characters.

      • Delving Deeper Book

        The subject of regular expressions is quite deep, and it takes an immense amount of practice to get used to the special character syntax. Furthermore, the re module contains a vast set of methods available for performing searches using regular expressions. Upon completing the examples in this section, you should have a much deeper appreciation for how powerful regular expressions can be.

    • 8.2: Processing File Data

      • Now, we will practice regular expressions and file handling. First, download this text file. After you download this file, upload it into the leftmost window in Repl.it to ensure file reads will be able to access the data.

      • Processing File Data Page

        Watch these videos and follow along using the file you just downloaded.

    • Study Session Video Review

    • Unit 8 Review and Assessment

      • Unit 8 Review Page

        In this video, course designer Eric Sakk walks through the major topics we covered in Unit 8. As you watch, work through the exercises to try them out yourself.

      • Unit 8 Assessment Quiz
        Receive a grade

        Take this assessment to see how well you understood this unit.

        • This assessment does not count towards your grade. It is just for practice!
        • You will see the correct answers when you submit your answers. Use this to help you study for the final exam!
        • You can take this assessment as many times as you want, whenever you want.