NormalizingKernel (BioJava-1.5-beta API)
Keywords: org.biojava.stats.svm.NormalizingKernel class

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## org.biojava.stats.svm
Class NormalizingKernel

    java.lang.Object
      org.biojava.stats.svm.NestedKernel
          org.biojava.stats.svm.NormalizingKernel

All Implemented Interfaces:
  Serializable, SVMKernel

    public class NormalizingKernel

extends NestedKernel

Performs a normalization on the results of a nested kernel.

This is equivalent to making the locations in feature space of the nested kernel unit vectors lying on a unit sphere. The dot product in feature space then becomes just `cos theta` rather than `||a|| * ||b|| * cos theta` as both lengths are 1. The length of a in the feature space of kernel k is `sqrt( k(a, a) )`, so that the normalizing kernel ends up calculating `k(a, b) / sqrt( k(a, a) * k(b, b) )`.

As the values of k(x, x) are required repeatedly, it may be worth making the nested kernel a DiagonalCachingKernel.

Author:
  Thomas Down, Matthew Pocock
See Also:
  Serialized Form

Constructor Summary
`NormalizingKernel()`
`NormalizingKernel(SVMKernel k)`

Method Summary
`double` | `evaluate(Object a, Object b)` Return the dot product of two vectors in an arbitrary feature space.
`String` | `toString()`

Methods inherited from class org.biojava.stats.svm.NestedKernel
`getNestedKernel, setNestedKernel`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Constructor Detail

### NormalizingKernel

    public NormalizingKernel()

### NormalizingKernel

    public NormalizingKernel(SVMKernel k)

Method Detail

### evaluate

    public double evaluate(Object a,
                           Object b)

  Description copied from interface: `SVMKernel`
  Return the dot product of two vectors in an arbitrary feature space. In this implementation, the `vectors' can actually be arbitrary objects.

### toString

    public String toString()

  Overrides:
    `toString` in class `Object`

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