smile.validation

Class Hyperparameters

java.lang.Object

smile.validation.Hyperparameters

public class Hyperparameters
extends java.lang.Object

Hyperparameter tuning. A hyperparameter is a parameter whose value is set before the learning process begins. By contrast, the values of other parameters are derived via training.

Hyperparameters can be classified as model hyperparameters, that cannot be inferred while fitting the machine to the training set because they refer to the model selection task, or algorithm hyperparameters, that in principle have no influence on the performance of the model but affect the speed and quality of the learning process. For example, the topology and size of a neural network are model hyperparameters, while learning rate and mini-batch size are algorithm hyperparameters.

The below example shows how to tune the hyperparameters of random forest.

 
    import smile.io.*;
    import smile.data.formula.Formula;
    import smile.validation.*;
    import smile.classification.RandomForest;

    var hp = new Hyperparameters()
        .add("smile.random.forest.trees", 100) // a fixed value
        .add("smile.random.forest.mtry", new int[] {2, 3, 4}) // an array of values to choose
        .add("smile.random.forest.max.nodes", 100, 500, 50); // range [100, 500] with step 50

    var train = Read.arff("data/weka/segment-challenge.arff");
    var test = Read.arff("data/weka/segment-test.arff");
    var formula = Formula.lhs("class");
    var testy = formula.y(test).toIntArray();

    hp.grid().forEach(prop -> {
        var model = RandomForest.fit(formula, train, prop);
        var pred = model.predict(test);
        System.out.println(prop);
        System.out.format("Accuracy = %.2f%%%n", (100.0 * Accuracy.of(testy, pred)));
        System.out.println(ConfusionMatrix.of(testy, pred));
    });
 
 

Constructor Summary

Constructors

Constructor and Description
Hyperparameters() Constructor.

Method Summary

Modifier and Type	Method and Description
Hyperparameters	add(java.lang.String name, double value) Adds a parameter.
Hyperparameters	add(java.lang.String name, double[] values) Adds a parameter.
Hyperparameters	add(java.lang.String name, double start, double end) Adds a parameter.
Hyperparameters	add(java.lang.String name, double start, double end, double step) Adds a parameter.
Hyperparameters	add(java.lang.String name, int value) Adds a parameter.
Hyperparameters	add(java.lang.String name, int[] values) Adds a parameter.
Hyperparameters	add(java.lang.String name, int start, int end) Adds a parameter.
Hyperparameters	add(java.lang.String name, int start, int end, int step) Adds a parameter.
Hyperparameters	add(java.lang.String name, java.lang.String value) Adds a parameter.
Hyperparameters	add(java.lang.String name, java.lang.String[] values) Adds a parameter.
java.util.stream.Stream<java.util.Properties>	grid() Generates a stream of hyperparameters for grid search.
java.util.stream.Stream<java.util.Properties>	random() Generates a stream of hyperparameters for random search.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Hyperparameters

public Hyperparameters()

Constructor.

Method Detail

add

public Hyperparameters add(java.lang.String name,
                           int value)

Adds a parameter.

Parameters:

name - the parameter name.

value - a fixed value of parameter.

Returns:

this object.

add

public Hyperparameters add(java.lang.String name,
                           double value)

Adds a parameter.

Parameters:

name - the parameter name.

value - a fixed value of parameter.

Returns:

this object.

add

public Hyperparameters add(java.lang.String name,
                           java.lang.String value)

Adds a parameter.

Parameters:

name - the parameter name.

value - a fixed value of parameter.

Returns:

this object.

add

public Hyperparameters add(java.lang.String name,
                           int[] values)

Adds a parameter.

Parameters:

name - the parameter name.

values - an array of parameter values.

Returns:

this object.

add

public Hyperparameters add(java.lang.String name,
                           double[] values)

Adds a parameter.

Parameters:

name - the parameter name.

values - an array of parameter values.

Returns:

this object.

add

public Hyperparameters add(java.lang.String name,
                           java.lang.String[] values)

Adds a parameter.

Parameters:

name - the parameter name.

values - an array of parameter values.

Returns:

this object.

add

public Hyperparameters add(java.lang.String name,
                           int start,
                           int end)

Adds a parameter.

Parameters:

name - the parameter name.

start - the start of value range (inclusive).

end - the end of value range (inclusive).

Returns:

this object.

add

public Hyperparameters add(java.lang.String name,
                           int start,
                           int end,
                           int step)

Adds a parameter.

Parameters:

name - the parameter name.

start - the start of value range (inclusive).

end - the end of value range (inclusive).

step - the step size.

Returns:

this object.

add

public Hyperparameters add(java.lang.String name,
                           double start,
                           double end)

Adds a parameter.

Parameters:

name - the parameter name.

start - the start of value range (inclusive).

end - the end of value range (inclusive).

Returns:

this object.

add

public Hyperparameters add(java.lang.String name,
                           double start,
                           double end,
                           double step)

Adds a parameter.

Parameters:

name - the parameter name.

start - the start of value range (inclusive).

end - the end of value range (inclusive).

step - the step size.

Returns:

this object.

random

public java.util.stream.Stream<java.util.Properties> random()

Generates a stream of hyperparameters for random search.

grid

public java.util.stream.Stream<java.util.Properties> grid()

Generates a stream of hyperparameters for grid search.