Package org.apache.lucene.search.similarities

# Class Lambda

java.lang.Object
org.apache.lucene.search.similarities.Lambda

Direct Known Subclasses:
  `LambdaDF`, `LambdaTTF`

public abstract class Lambda extends Object
The lambda (λw) parameter in information-based models.

See Also:
  - `IBSimilarity`
WARNING: This API is experimental and might change in incompatible ways in the next release.

## Constructor Summary

Constructors
Constructor
Description
`Lambda()`
Sole constructor.

## Method Summary

Modifier and Type
Method
Description
`abstract Explanation`
`explain(BasicStats stats)`
Explains the lambda parameter.
`abstract float`
`lambda(BasicStats stats)`
Computes the lambda parameter.
`abstract String`
`toString()`
Subclasses must override this method to return the code of the lambda formula.

### Methods inherited from class java.lang.Object

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

## Constructor Details

### Lambda

public Lambda()
Sole constructor. (For invocation by subclass constructors, typically implicit.)

## Method Details

### lambda

public abstract float lambda(BasicStats stats)
Computes the lambda parameter.

### explain

public abstract Explanation explain(BasicStats stats)
Explains the lambda parameter.

### toString

public abstract String toString()
Subclasses must override this method to return the code of the lambda formula. Since the original paper is not very clear on this matter, and also uses the DFR naming scheme incorrectly, the codes here were chosen arbitrarily.

Overrides:
  `toString` in class `Object`