SimpleMatrixSelect (JaCoP 4.9.0 API)

java.lang.Object
- org.jacop.search.SimpleMatrixSelect<T>

Type Parameters:

T - type of variable being used in the Search.

All Implemented Interfaces:

SelectChoicePoint<T>
```
public class SimpleMatrixSelect<T extends Var>
extends Object
implements SelectChoicePoint<T>
```
SimpleMatrixSelect selects first a row in the matrix based on metric of the variable at pivotPosition. As soon as a row is choosen, variables starting from the beginning of the row which are not assigned yet are selected. The row selection is done with the help of variable comparators. Two comparators can be employed main and tiebreaking one. If two are not sufficient to differentiate two rows than the lexigraphical ordering is used.
Default values: pivotPosition = 0, mainComparator = InputOrder, tieBreakingComparator = InputOrder.

Version:

4.9

Author:

Radoslaw Szymanek and Krzysztof Kuchcinski

Field Summary

Fields
Modifier and Type	Field and Description
`boolean`	`inputOrderTieBreaking` It decides if input order tiebreaking is used.
`int`	`pivotPosition` It specifies the pivot position (first element has index 0).
`Map<T,Integer>`	`position` It stores the original positions of variables to be used for input order tie-breaking.
`List<List<T>>`	`searchVariables` It stores variables which need to be labelled.

Constructor Summary

Constructors
Constructor and Description
`SimpleMatrixSelect(T[][] vars, ComparatorVariable<T> mainComparator, ComparatorVariable<T> tieBreakingComparator, Indomain<T> indomain)` It constructs a MatrixSelection variable ordering.
`SimpleMatrixSelect(T[][] vars, ComparatorVariable<T> mainComparator, ComparatorVariable<T> tieBreakingComparator, Indomain<T> indomain, int pivotPosition)` This constructor allows to specify all parameters for the selection mechanism.
`SimpleMatrixSelect(T[][] vars, ComparatorVariable<T> mainComparator, Indomain<T> indomain)` It constructs a MatrixSelection variable ordering.
`SimpleMatrixSelect(T[][] vars, Indomain<T> indomain)` This constructor uses default values for all parameters.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`PrimitiveConstraint`	`getChoiceConstraint(int index)` It always returns null as choice point is obtained by getChoiceVariable and getChoiceValue.
`int`	`getChoiceValue()` It returns a value which is the base of the next choice point.
`T`	`getChoiceVariable(int firstVariable)` It returns the variable which is the base on the next choice point.
`int`	`getIndex()` It returns the current index.
`int`	`getPivotPosition()` It returns the position of the pivot variable.
`Map<T,Integer>`	`getVariablesMapping()` It returns the variables for which assignment in the solution is given.
`void`	`setDynamicLexTieBreaking()` It uses cheap method of breaking the ties.
`void`	`setInputOrderTieBreaking()` It chooses input order tiebreaking if the supplied comparators can not distinguish between matrix rows.
`String`	`toString()`

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

- Field Detail
  - inputOrderTieBreaking
```
public boolean inputOrderTieBreaking
```
    It decides if input order tiebreaking is used. If input tiebreaking is not used than the current arrangement of row, variables within rows decides on the priority. The arrangement of the rows, variables within rows depends on the search history. Setting it to false makes the final tiebreaking a mixture of input-order/search history influenced tie breaking. It is faster to compute tiebreaking and it may give interesting search history based tiebreaking.
  - pivotPosition
```
public int pivotPosition
```
    It specifies the pivot position (first element has index 0).
  - position
```
public Map<T extends Var,Integer> position
```
    It stores the original positions of variables to be used for input order tie-breaking.
  - searchVariables
```
public List<List<T extends Var>> searchVariables
```
    It stores variables which need to be labelled.
- Constructor Detail
  - SimpleMatrixSelect
```
public SimpleMatrixSelect(T[][] vars,
                          Indomain<T> indomain)
```
    This constructor uses default values for all parameters. The size of the sublist is equal to two. The pivot position points to the first element. The tiebreaking delete used is DeleteMostConstrainedStatic.
    
    Parameters:
    
    vars - variables to choose from.
    
    indomain - value ordering heuristic used to choose a value for a given variable.
  - SimpleMatrixSelect
```
public SimpleMatrixSelect(T[][] vars,
                          ComparatorVariable<T> mainComparator,
                          Indomain<T> indomain)
```
    It constructs a MatrixSelection variable ordering.
    
    Parameters:
    
    vars - matrix of variables to be selected from.
    
    mainComparator - the variable comparator to choose the proper vector.
    
    indomain - variable ordering value to be used to determine value for a given variable.
  - SimpleMatrixSelect
```
public SimpleMatrixSelect(T[][] vars,
                          ComparatorVariable<T> mainComparator,
                          ComparatorVariable<T> tieBreakingComparator,
                          Indomain<T> indomain)
```
    It constructs a MatrixSelection variable ordering.
    
    Parameters:
    
    vars - matrix of variables to be selected from.
    
    mainComparator - the variable comparator to choose the proper vector.
    
    tieBreakingComparator - the variable comparator used if the main comparator can not distinguish between vectors.
    
    indomain - variable ordering value to be used to determine value for a given variable.
  - SimpleMatrixSelect
```
public SimpleMatrixSelect(T[][] vars,
                          ComparatorVariable<T> mainComparator,
                          ComparatorVariable<T> tieBreakingComparator,
                          Indomain<T> indomain,
                          int pivotPosition)
```
    This constructor allows to specify all parameters for the selection mechanism. Specifying mainComparator or tieBreaking to value null do not use that functionality of the selection mechanims.
    
    Parameters:
    
    vars - variables from which the base of the choice point is choosen.
    
    mainComparator - the main variable comparator used to compare variables.
    
    tieBreakingComparator - the secondary variable comparator used to break ties.
    
    indomain - the value ordering heuristic used to assign value to a chosen variable.
    
    pivotPosition - the position of the variable which is used to rank the rows.
- Method Detail
  - getChoiceVariable
```
public T getChoiceVariable(int firstVariable)
```
    It returns the variable which is the base on the next choice point. Only if choice is of an X = C type. This function returns null if all variables have a value assigned or a choice point based on other type of constraint is being selected. The parameter index is the last value which have been return by this SelectChoicePoint object which has not been backtracked upon yet.
    
    Specified by:
    
    getChoiceVariable in interface SelectChoicePoint<T extends Var>
    
    Parameters:
    
    firstVariable - the position of the last variable in selection choice point heuristic.
    
    Returns:
    
    variable based on which the choice needs to be created.
  - getChoiceValue
```
public int getChoiceValue()
```
    It returns a value which is the base of the next choice point. Only if choice is of an X = C type.
    
    Specified by:
    
    getChoiceValue in interface SelectChoicePoint<T extends Var>
    
    Returns:
    
    value used in the choice point (value).
  - getChoiceConstraint
```
public PrimitiveConstraint getChoiceConstraint(int index)
```
    It always returns null as choice point is obtained by getChoiceVariable and getChoiceValue.
    
    Specified by:
    
    getChoiceConstraint in interface SelectChoicePoint<T extends Var>
    
    Parameters:
    
    index - the position of the last variable returned by selection choice point heuristic.
    
    Returns:
    
    primitive constraint which is a base of a choice point.
  - getVariablesMapping
```
public Map<T,Integer> getVariablesMapping()
```
    It returns the variables for which assignment in the solution is given.
    
    Specified by:
    
    getVariablesMapping in interface SelectChoicePoint<T extends Var>
    
    Returns:
    
    mapping of variables to the positions in the variables array.
  - getIndex
```
public int getIndex()
```
    It returns the current index. Supplying this value in the next invocation of select will make search for next variable faster without comprimising efficiency.
    
    Specified by:
    
    getIndex in interface SelectChoicePoint<T extends Var>
    
    Returns:
    
    internal position of the last variable chosen to be the base of the choice point.
  - getPivotPosition
```
public int getPivotPosition()
```
    It returns the position of the pivot variable.
    
    Returns:
    
    the position of the pivot variable.
  - setDynamicLexTieBreaking
```
public void setDynamicLexTieBreaking()
```
    It uses cheap method of breaking the ties. It is based on input order influenced by the search history.
  - setInputOrderTieBreaking
```
public void setInputOrderTieBreaking()
```
    It chooses input order tiebreaking if the supplied comparators can not distinguish between matrix rows.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class SimpleMatrixSelect<T extends Var>

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

inputOrderTieBreaking

pivotPosition

position

searchVariables

Constructor Detail

SimpleMatrixSelect

SimpleMatrixSelect

SimpleMatrixSelect

SimpleMatrixSelect

Method Detail

getChoiceVariable

getChoiceValue

getChoiceConstraint

getVariablesMapping

getIndex

getPivotPosition

setDynamicLexTieBreaking

setInputOrderTieBreaking

toString