Markov Chain

Model Markov Chains in Python with NumPy for Smarter Data Workflows

A three-state writing workflow, drafting, revising, and publishing, makes an ideal test case for understanding Markov chains.

3 min readTowards Data Science

Markov chains are one of those concepts that sound more intimidating than they actually are, and that's exactly why the recent guide on building them in Python with NumPy matters. We think it's a genuinely useful resource for anyone who wants to move beyond static spreadsheets and into probabilistic modeling that reflects how real-world systems behave. The three-state writing example, modeling transitions between drafting, editing, and publishing, is the kind of concrete scenario that makes the math feel immediately relevant rather than abstract.

This approach aligns with what we've been seeing across data work: the tools that win are the ones that reduce friction between thinking and doing. For instance, a recent piece on Explore embeddings through the geometry of cosine similarity explained simply showed how geometric intuition can demystify vector comparisons, much like transition matrices make state prediction tangible. And when we look at Practical Python for automating four real-world image decisions, the same principle applies: give people straightforward code that solves a specific problem, and they'll adopt it. The Markov chain tutorial does exactly that, it hands you a working implementation for the Chapman, Kolmogorov equation and stationary distributions without burying you in theory first.

What stands out here is the choice of NumPy. It's not flashy, but it's accessible, and that matters. You don't need a specialized probabilistic programming library to start modeling sequences. You need matrix multiplication and a clear understanding of what a transition matrix represents. The guide walks through each step, from building the matrix to computing multi-step probabilities, and then lands on the stationary distribution, the long-run behavior that tells you, in the writing example, what fraction of time you'll likely spend in each stage. That's a concrete output with real utility: project managers can use it to forecast workflow bottlenecks, writers can estimate completion timelines, and analysts can apply the same logic to customer journeys or system states.

The takeaway is straightforward: if you can multiply matrices in NumPy, you can build a Markov chain. The guide proves that by starting with a three-state model and showing how to extend it. The specific thing to watch is how the stationary distribution changes when you alter even one transition probability, it reveals how sensitive these models are to small changes in behavior. That sensitivity is exactly why they're powerful, and why this tutorial is worth your time.

From Towards Data Science

A step-by-step guide to transition matrices, the Chapman–Kolmogorov equation, and stationary distributions, built around a three-state writing example.

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