DistantSamplerState

java.lang.Object
- DistantSamplerState

All Implemented Interfaces:

java.lang.Cloneable, State
```
public class DistantSamplerState
extends java.lang.Object
implements State, java.lang.Cloneable
```
DistantSamplerState - Stochastic local search state for finding a sample of data points from a set of data points that minimize the sum of inverse-squared Euclidean distances between pairs of data points. For example, suppose the constructor is initialized with 100 two-dimensional points and one wishes to select 10 samples from such points so as to have them maximally spread apart from each other. This can be accomplished by finding a subset of 10 data points that minimize the following energy measure: For each pair of points, compute the Euclidean distance between them. Compute the reciprocal of the square of this distance and consider it to be the "energy" between these two points. Next, sum all such "energies" between all pairs of points and designate this to be the overall energy of the state of sample selection. Note: When adding the energy from sampled points A and B, make sure A is different than B, and do not then redundantly add the energy from B and A. Count each distinct sample pair once.
step() specification: Pick a random sample and change it to a different sample that is distinct from the rest.

undo() specification: Undo the change of the previous step() call. You may assume that there is at least one step() call between each undo() call, that is, you are only required to undo the most recent step.

energy() specification: Return the sum of inverse-squared Euclidean distances between pairs of data points.

clone() specification: Perform a deep clone of this DistantSamplerState, such that changes to the copy do not affect the original or vice versa.

toString() specification: Return the standard Java String representation of getSampleIndices().

Constructor Summary

Constructors
Constructor and Description
`DistantSamplerState(double[][] data, int numSamples)` Initializes the current sample selection to be `numSamples` unique indices to the data array.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`DistantSamplerState`	`clone()`
`double`	`energy()`
`int[]`	`getSampleIndices()` Return a sorted list of the indices of data points chosen for the current sample.
`void`	`step()`
`java.lang.String`	`toString()`
`void`	`undo()`

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

- Constructor Detail
  - DistantSamplerState
```
public DistantSamplerState(double[][] data,
                           int numSamples)
```
    Initializes the current sample selection to be numSamples unique indices to the data array.
    
    Parameters:
    
    data - - a rectangular 2D array with each row being a single datum vector, and the columns 0 through n - 1 being the vector elements of an n-dimensional vector.
    
    numSamples - - the number of sample selections to make from this data, that is, the number of data rows to be selected.
- Method Detail
  - step
```
public void step()
```
    Specified by:
    
    step in interface State
  - undo
```
public void undo()
```
    Specified by:
    
    undo in interface State
  - energy
```
public double energy()
```
    Specified by:
    
    energy in interface State
  - clone
```
public DistantSamplerState clone()
```
    Specified by:
    
    clone in interface State
    
    Overrides:
    
    clone in class java.lang.Object
  - getSampleIndices
```
public int[] getSampleIndices()
```
    Return a sorted list of the indices of data points chosen for the current sample. This should be a sorted subset of the numbers [0, data.length - 1].
    
    Returns:
    
    a sorted list of the indices of data points chosen for the current sample
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object

Class DistantSamplerState

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

DistantSamplerState

Method Detail

step

undo

energy

clone

getSampleIndices

toString