Guides
Deep dives, written to be understood
Long-form guides on the ideas that trip people up — each one pairs with an interactive module where you run the code yourself.
Guide 9 min read
Pandas GroupBy, Explained the Way You Wish It Had Been
Split-apply-combine is three ideas, not one. A practical tour of groupby, agg, transform, and the mistakes everyone makes on the way.
Read the guide Guide 10 min read
Your First Machine Learning Model, End to End
From raw CSV to honest accuracy number with scikit-learn — including the two mistakes that make beginners' models look better than they are.
Read the guide Guide 8 min read
NumPy Broadcasting: The Mental Model That Makes It Click
Broadcasting isn't magic — it's two rules applied right-to-left. Learn to predict shapes before you run the code, and shape errors stop being mysterious.
Read the guide Guide 11 min read
How to Actually Learn Data Science in 2026 (Without Drowning)
The field looks infinite from the outside. The hireable core is small. A realistic 6-month sequence, what to skip, and how AI tools change the job.
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