Isolation Forest

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Isolation Forest finds strange items by seeing which ones are easy to separate from the rest.

What it does

Isolation Forest finds strange items by seeing which ones are easy to separate from the rest.

Anomaly: Something broken or weird • Isolation: Being separated

How it works

  • Split the data again and again.
  • Count how quickly each item gets separated alone.
  • Items separated very quickly may be unusual.

Uses and applications

  • A bank can flag a strange credit card purchase for review.
  • A factory can notice a machine reading that looks different from normal.
  • A game can spot player behavior that may need checking.

In short

It catches fraud or failing machines by finding unusual data.

Related methods

  • DBSCAN: Also separates outliers, as noise points outside dense groups.
  • Random Forest: Uses many trees too, but to predict labels.

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