Curtly Critchlow

“At first, I kind of wanted videos. But it didn’t take long to realize that the Dataquest approach was working. I felt I was learning more by reading, and that it was giving me good practice for reading software documentation (which is rarely available in video tutorial form).”

Curtly Critchlow

Safety Security Officer @Nabi-KCL

Course overview

This course builds upon the fundamentals of Python taught in Introduction to Python Programming and For Loops and Conditional Statements in Python. You’ll learn how to create Python dictionaries, which are important data structures in Python that help gather elements for identification using a key. You’ll also learn how to build frequency tables, which help to display the frequencies of different categories (particularly useful for understanding the distribution of values in a dataset). Finally, you’ll learn how to write Python functions, which will help you perform a single, related action on a specific set of data.

Best of all, you’ll learn by doing — you’ll practice and get feedback directly in the browser. You’ll apply your skills to several guided projects involving realistic business scenarios to build your portfolio and prepare for your next interview.

Key skills

  • Creating Python dictionaries
  • Building frequency tables
  • Writing Python functions
  • Performing real-world data analysis tasks in an interactive coding environment

Course outline

Dictionaries, Frequency Tables, and Functions in Python [4 lessons]

Python Dictionaries 1h

Lesson Objectives
  • Create dictionaries
  • Index dictionaries
  • Define key-value pairs

Python Dictionaries and Frequency Tables 2h

Lesson Objectives
  • Update dictionary values
  • Check for values in a dictionary
  • Count with dictionaries
  • Loop over dictionaries

Python Functions: Using Built-in Functions and Creating Functions 1h

Lesson Objectives
  • Define the structure of a function
  • Create your own functions
  • Employ built-in functions
  • Return values from a function call

Python Functions: Arguments, Parameters, and Debugging 1h

Lesson Objectives
  • Reuse a function with different data inputs
  • Specify multiple function parameters
  • Employ keyword and positional arguments
  • Combine functions
  • Debug functions

The Dataquest guarantee


Dataquest has helped thousands of people start new careers in data. If you put in the work and follow our path, you’ll master data skills and grow your career.


We believe so strongly in our paths that we offer a full satisfaction guarantee. If you complete a career path on Dataquest and aren’t satisfied with your outcome, we’ll give you a refund.

Master skills faster with Dataquest

Go from zero to job-ready

Go from zero to job-ready

Learn exactly what you need to achieve your goal. Don’t waste time on unrelated lessons.

Build your project portfolio

Build your project portfolio

Build confidence with our in-depth projects, and show off your data skills.

Challenge yourself with exercises

Challenge yourself with exercises

Work with real data from day one with interactive lessons and hands-on exercises.

Showcase your path certification

Showcase your path certification

Impress employers by completing a capstone project and certifying it with an expert review.

Learning resources

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Aaron Melton

Business Analyst at Aditi Consulting

“Dataquest starts at the most basic level, so a beginner can understand the concepts. I tried learning to code before, using Codecademy and Coursera. I struggled because I had no background in coding, and I was spending a lot of time Googling. Dataquest helped me actually learn.”


Jessica Ko

Machine Learning Engineer at Twitter

“I liked the interactive environment on Dataquest. The material was clear and well organized. I spent more time practicing then watching videos and it made me want to keep learning.”


Victoria E. Guzik

Associate Data Scientist at Callisto Media

“I really love learning on Dataquest. I looked into a couple of other options and I found that they were much too handhold-y and fill in the blank relative to Dataquest’s method. The projects on Dataquest were key to getting my job. I doubled my income!”

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