cc.mallet.grmm.types
Class ConstantFactor

java.lang.Object
  cc.mallet.grmm.types.AbstractFactor
      cc.mallet.grmm.types.ConstantFactor

All Implemented Interfaces:

Factor, java.io.Serializable, java.lang.Cloneable

public class ConstantFactor
extends AbstractFactor

$Id: ConstantFactor.java,v 1.1 2007/10/22 21:37:44 mccallum Exp $

See Also:

Serialized Form

Field Summary

Fields inherited from class cc.mallet.grmm.types.AbstractFactor

vars

Constructor Summary

ConstantFactor(double c)

Method Summary

boolean	almostEquals(Factor p, double epsilon)
java.lang.String	dumpToString()
Factor	duplicate()
protected Factor	extractMaxInternal(VarSet varSet)
boolean	isNaN()
protected double	lookupValueInternal(int i)
static Factor	makeIdentityFactor()
protected Factor	marginalizeInternal(VarSet varsToKeep)
Factor	multiply(Factor other) Returns the elementwise product of this factor with another.
void	multiplyBy(Factor other) Does this *= pot.
Factor	normalize() Multiplies this potential by a constant such that it sums to 1.
Assignment	sample(Randoms r) Return an assignment sampled from this factor, interpreting it as an unnormalized probability distribution.
Factor	slice(Assignment assn)
java.lang.String	toString()
double	value(AssignmentIterator it) Returns the probability of an assignment to these variables.

Methods inherited from class cc.mallet.grmm.types.AbstractFactor

almostEquals, argmax, assignmentIterator, asTable, containsVar, delogify, divideBy, entropy, exponentiate, extractMax, extractMax, extractMax, getVariable, isInLogSpace, log, logify, logValue, logValue, logValue, marginalize, marginalize, marginalize, marginalizeOut, marginalizeOut, phi, prettyOutputString, setVarSet, sum, value, varSet

Methods inherited from class java.lang.Object

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

Constructor Detail

ConstantFactor

public ConstantFactor(double c)

Method Detail

extractMaxInternal

protected Factor extractMaxInternal(VarSet varSet)

Specified by:

extractMaxInternal in class AbstractFactor

lookupValueInternal

protected double lookupValueInternal(int i)

Specified by:

lookupValueInternal in class AbstractFactor

marginalizeInternal

protected Factor marginalizeInternal(VarSet varsToKeep)

Specified by:

marginalizeInternal in class AbstractFactor

value

public double value(AssignmentIterator it)

Description copied from interface: Factor

Returns the probability of an assignment to these variables. The assignment used is the curret assignment from the given AssignmentIterator.

This can be used to do things like

         DiscretePotential phi = createMyPtl ();
         for (AssignmentIterator it = phi.assignmentIterator; it.hasNext(); it.advance()) {
           double val = ptl.phi (it);
                 // do something with val
   }
  

This is equivalent to creating an assignment object explicitly using (Assignment) it.next(), but can be much faster.

Specified by:

value in interface Factor

Overrides:

value in class AbstractFactor

normalize

public Factor normalize()

Description copied from interface: Factor

Multiplies this potential by a constant such that it sums to 1. Destructive; returns this factor.

sample

public Assignment sample(Randoms r)

Description copied from interface: Factor

Return an assignment sampled from this factor, interpreting it as an unnormalized probability distribution.

Specified by:

sample in interface Factor

Overrides:

sample in class AbstractFactor

dumpToString

public java.lang.String dumpToString()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

slice

public Factor slice(Assignment assn)

duplicate

public Factor duplicate()

almostEquals

public boolean almostEquals(Factor p,
                            double epsilon)

isNaN

public boolean isNaN()

multiply

public Factor multiply(Factor other)

Description copied from interface: Factor

Returns the elementwise product of this factor with another.

Specified by:

multiply in interface Factor

Overrides:

multiply in class AbstractFactor

multiplyBy

public void multiplyBy(Factor other)

Description copied from interface: Factor

Does this *= pot.

If both potentials are currently in log space, then does addition instead.

Specified by:

multiplyBy in interface Factor

Overrides:

multiplyBy in class AbstractFactor

makeIdentityFactor

public static Factor makeIdentityFactor()