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NumPy

The array library nearly all scientific Python builds on.

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This course has 4 lessons. Start with the first one and use the next / previous links at the bottom of each lesson — the sidebar keeps the whole course in order.

Lessons

  1. NumPy arraysWhy ndarray exists, how shapes and dtypes work, and how to create arrays in the ways you will actually use.
  2. Indexing, slicing and masksBasic slicing, views versus copies, boolean masks and fancy indexing — plus the assignment rule that catches everyone.
  3. Vectorised maths and broadcastingElement-wise operations, the ufunc model, aggregation, and the broadcasting rules that make array code concise.
  4. Reshaping, stacking and splittingreshape, transpose, concatenate and split — how to move data between shapes without copying more than necessary.

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Last refreshed 2026-09-17.