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Anomaly Detection

Score isolation paths

BOTIE

Average paths, divide by the normaliser, negate, then raise two to that exponent.
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Context for this challenge

Average paths, divide by the normaliser, negate, then raise two to that exponent.

Botie has each fitted tree's isolation path length for one reading. Short paths indicate that relatively few partitions separated it.

Average the tree paths, divide by the supplied positive normaliser, negate, and raise two to that exponent.

Examples and results
Paths across trees
  1. 01
  2. 11
Positive c(n)
2
Required result
0.7071
Paths across trees
  1. 02
  2. 12
Positive c(n)
2
Required result
0.5
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Assumptions and test precision

Paths must come from fitted trees with a consistent subsample size and leaf correction policy. Numerical tests allow a difference of 0.001. Lists and structures must also have the right shape.

Some trees isolate the reading sooner

This check uses the pieces from “Convert isolation paths into a comparable score”.

BOTIE

Across three isolation trees, Botie's reading reaches isolation at path lengths 2, 4 and 6. Calculate the isolation score using supplied normaliser 4. Average path lengths before applying the exponential.
Paths across trees
  1. 02
  2. 14
  3. 26
Positive c(n)
4

Use a number, text, or an array matching the requested result. For a matrix, put each row in brackets. Saving your prediction runs your current construction on these inputs and checks the earlier examples too.

Build a construction in the workspace above first. This case will test those pieces.

Why should path lengths from incompatible subsample sizes not share an arbitrary normaliser?

An isolation score depends on the fitted trees' sampling and path-correction conventions.

Paths must come from fitted trees with a consistent subsample size and leaf correction policy.

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