Unsupervised Anomaly Detection

Introduction using Python

Diogo Ribeiro
20 min readApr 22, 2024
Photo by Markus Spiske on Unsplash

Anomaly detection, a fundamental aspect of machine learning, is instrumental in identifying unusual patterns or data points that deviate significantly from the norm. These anomalies often signal critical, actionable insights, ranging from fraud detection in financial transactions to early warnings in system health monitoring, making anomaly detection pivotal across a spectrum of industries. Its importance cannot be overstated; in cybersecurity, for instance, it helps in the early detection of breaches or malicious activities by spotting irregularities in user behaviors or network traffic. In healthcare, anomaly detection algorithms can flag unusual patient readings, facilitating early intervention for conditions that might otherwise go unnoticed until they become severe.

Unsupervised learning plays a crucial role in anomaly detection, especially in scenarios where there is a lack of labeled data — a common situation in many real-world applications. Unlike supervised learning, where models are trained on a pre-labeled dataset containing both normal and anomalous examples, unsupervised learning algorithms must make sense of the data without any such guidance. This presents a significant challenge: without labels, how does one differentiate between normal and abnormal? Unsupervised anomaly detection algorithms navigate this…

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