## Uses of Interface
org.apache.ignite.ml.tree.impurity.ImpurityMeasure

- Packages that use ImpurityMeasure
  Package | Description
  --- | ---
  org.apache.ignite.ml.tree | Root package for decision trees.
  org.apache.ignite.ml.tree.impurity | Root package for decision tree impurity measures and calculators.
  org.apache.ignite.ml.tree.impurity.gini | Contains Gini impurity measure and calculator.
  org.apache.ignite.ml.tree.impurity.mse | Contains mean squared error impurity measure and calculator.
  org.apache.ignite.ml.tree.impurity.util | Contains util classes used in decision tree impurity calculators.

- - ### Uses of ImpurityMeasure in org.apache.ignite.ml.tree

    Classes in org.apache.ignite.ml.tree with type parameters of type ImpurityMeasure
    Modifier and Type | Class and Description
    --- | ---
    `class` | `DecisionTreeTrainer<T extends ImpurityMeasure<T>>` Distributed decision tree trainer that allows to fit trees using row-partitioned dataset.

  - ### Uses of ImpurityMeasure in org.apache.ignite.ml.tree.impurity

    Classes in org.apache.ignite.ml.tree.impurity with type parameters of type ImpurityMeasure
    Modifier and Type | Interface and Description
    --- | ---
    `interface` | `ImpurityMeasure<T extends ImpurityMeasure<T>>` Base interface for impurity measures that can be used in distributed decision tree algorithm.
    `class` | `ImpurityMeasureCalculator<T extends ImpurityMeasure<T>>` Base interface for impurity measure calculators that calculates all impurity measures required to find a best split.

  - ### Uses of ImpurityMeasure in org.apache.ignite.ml.tree.impurity.gini

    Classes in org.apache.ignite.ml.tree.impurity.gini that implement ImpurityMeasure
    Modifier and Type | Class and Description
    --- | ---
    `class` | `GiniImpurityMeasure` Gini impurity measure which is calculated the following way: `\-frac{1}{L}\sum_{i=1}^{s}l_i^2 - \frac{1}{R}\sum_{i=s+1}^{n}r_i^2`.

  - ### Uses of ImpurityMeasure in org.apache.ignite.ml.tree.impurity.mse

    Classes in org.apache.ignite.ml.tree.impurity.mse that implement ImpurityMeasure
    Modifier and Type | Class and Description
    --- | ---
    `class` | `MSEImpurityMeasure` Mean squared error (variance) impurity measure which is calculated the following way: `\frac{1}{L}\sum_{i=0}^{n}(y_i - \mu)^2`.

  - ### Uses of ImpurityMeasure in org.apache.ignite.ml.tree.impurity.util

    Classes in org.apache.ignite.ml.tree.impurity.util with type parameters of type ImpurityMeasure
    Modifier and Type | Class and Description
    --- | ---
    `class` | `SimpleStepFunctionCompressor<T extends ImpurityMeasure<T>>` Simple step function compressor.
    `class` | `StepFunction<T extends ImpurityMeasure<T>>` Step function described by `x` and `y` points.
    `interface` | `StepFunctionCompressor<T extends ImpurityMeasure<T>>` Base interface for step function compressors which reduces step function size.

    Methods in org.apache.ignite.ml.tree.impurity.util that return ImpurityMeasure
    Modifier and Type | Method and Description
    --- | ---
    `T[]` | StepFunction.`getY()`

    Constructors in org.apache.ignite.ml.tree.impurity.util with parameters of type ImpurityMeasure
    Constructor and Description
    `StepFunction(double[] x, T[] y)` Constructs a new instance of step function.

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Release Date | : January 10 2022