de.jstacs.algorithms.graphs.tensor
Class Tensor

java.lang.Object
  de.jstacs.algorithms.graphs.tensor.Tensor

Direct Known Subclasses:

AsymmetricTensor, SubTensor, SymmetricTensor

public abstract class Tensor
extends Object

This is the super class for any tensor. The tensor may be symmetric or asymmetric.

Author:

Jens Keilwagen

See Also:

AsymmetricTensor, SymmetricTensor

Field Summary

protected int	L The number of nodes minus 1.
protected byte	order The order of the tensor.
protected int[]	powers An array containing the powers for the number of nodes.

Constructor Summary

Tensor(int n, byte k)
Creates a new Tensor for n nodes and order k.

Method Summary

protected int	getAsymIndex(int child, int[] parents, byte k) Returns the index for an asymmetric tensor.
abstract int[]	getMaximalEdgeFor(byte k, int child, int... parents) Returns the edge permute(parents[0],...
int	getNumberOfNodes() Returns the number of nodes.
byte	getOrder() Returns the order.
abstract double	getRootValue(int child) Returns the value for child as root.
abstract double	getValue(byte k, int child, int... parents) Returns the value for the edge parents[0],...
static Tensor	readTensorFromFile(String fname, boolean asym) The opposite of the method writeTensorToFile(String, OutputStream).
abstract void	resetValue(byte k, int child, int... parents) Sets the value for the edge parents[0],...
abstract void	setRootValue(int child, double val) Sets the value val for the root node child.
abstract void	setValue(byte k, double val, int child, int... parents) Sets the value for the edge parents[0],...
double[][][]	toDouble3DArray() Creates a three-dimensional double array representation of the Tensor.
void	writeTensorToFile(String fname, OutputStream desc) This method writes a Tensor in the exchange format in a specified file.

Methods inherited from class java.lang.Object

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

Field Detail

powers

protected int[] powers

An array containing the powers for the number of nodes. This might be used in the computation of some indices.

L

protected int L

The number of nodes minus 1.

order

protected byte order

The order of the tensor.

Constructor Detail

Tensor

public Tensor(int n,
              byte k)
       throws IllegalArgumentException

Creates a new Tensor for n nodes and order k.

Parameters:

n - the number of nodes

k - the order

Throws:

IllegalArgumentException - if n < 0 or k < 1

Method Detail

getMaximalEdgeFor

public abstract int[] getMaximalEdgeFor(byte k,
                                        int child,
                                        int... parents)

Returns the edge permute(parents[0],...,parents[k-1]) -> child that maximizes the score.

Parameters:

k - the number of parents to be used

child - the child node

parents - the parent nodes (only the first k will be used)

Returns:

the edge permute(parents[0],...,parents[k-1]) -> child that maximizes the score

getNumberOfNodes

public int getNumberOfNodes()

Returns the number of nodes.

Returns:

the number of nodes

getOrder

public byte getOrder()

Returns the order.

Returns:

the order.

getRootValue

public abstract double getRootValue(int child)

Returns the value for child as root.

Parameters:

child - the name of the node

Returns:

the value for the node

getValue

public abstract double getValue(byte k,
                                int child,
                                int... parents)

Returns the value for the edge parents[0],...,parents[k-1] -> child.

Parameters:

k - the number of parents to be used

child - the child node

parents - the parent nodes (only the first k will be used)

Returns:

the value for the edge parents[0],...,parents[k-1] -> child

setRootValue

public abstract void setRootValue(int child,
                                  double val)

Sets the value val for the root node child.

Parameters:

child - the name of the node

val - the value for the node

setValue

public abstract void setValue(byte k,
                              double val,
                              int child,
                              int... parents)

Sets the value for the edge parents[0],...,parents[k-1] -> child.

Parameters:

k - the number of parents to be used

val - the new value

child - the child node

parents - the parent nodes (only the first k will be used)

resetValue

public abstract void resetValue(byte k,
                                int child,
                                int... parents)

Sets the value for the edge parents[0],...,parents[k-1] -> child to Double.NEGATIVE_INFINITY.

Parameters:

k - the number of parents to be used

child - the child node

parents - the parent nodes (only the first k will be used)

writeTensorToFile

public void writeTensorToFile(String fname,
                              OutputStream desc)
                       throws IOException

This method writes a Tensor in the exchange format in a specified file.

Parameters:

fname - the file name

desc - gives you the possibility to write the description of the tensor file

Throws:

IOException - if something went wrong with the file

See Also:

readTensorFromFile(String, boolean)

readTensorFromFile

public static Tensor readTensorFromFile(String fname,
                                        boolean asym)
                                 throws NumberFormatException,
                                        IOException

The opposite of the method writeTensorToFile(String, OutputStream).

Parameters:

fname - the file name

asym - true generates an AsymmetricTensor, otherwise a SymmetricTensor

Returns:

the tensor from the file

Throws:

IOException - if something went wrong with the file

NumberFormatException - if the file could not be parsed correctly

See Also:

writeTensorToFile(String, OutputStream)

toDouble3DArray

public double[][][] toDouble3DArray()

Creates a three-dimensional double array representation of the Tensor.

Returns:

a three-dimensional double array representation of the Tensor

getAsymIndex

protected int getAsymIndex(int child,
                           int[] parents,
                           byte k)

Returns the index for an asymmetric tensor.

Parameters:

child - the child node

parents - the parent notes

k - the order

Returns:

the index for an asymmetric tensor

See Also:

powers