edu.illinois.cs.cogcomp.infer.ilp

Class OJalgoHook

java.lang.Object

edu.illinois.cs.cogcomp.infer.ilp.OJalgoHook

All Implemented Interfaces:

ILPSolver

public class OJalgoHook
extends Object
implements ILPSolver

A hook for the oj! Algorithms (ojAlgo), an Open Source Java code to do mathematics, linear algebra and optimisation. For further information, see http://ojalgo.org/

Field Summary

Fields inherited from interface edu.illinois.cs.cogcomp.infer.ilp.ILPSolver

VERBOSITY_HIGH, VERBOSITY_LOW, VERBOSITY_NONE

Constructor Summary

Constructors

Constructor and Description
OJalgoHook()

Method Summary

Modifier and Type	Method and Description
int	addBooleanVariable(double c) Adds a new Boolean variable (an integer variable constrained to take either the value 0 or the value 1) with the specified coefficient in the objective function to the problem.
int[]	addDiscreteVariable(double[] c) Adds a general, multi-valued discrete variable, which is implemented as a set of Boolean variables, one per value of the discrete variable, with exactly one of those variables set true at any given time.
void	addEqualityConstraint(int[] i, double[] a, double b) Adds a new fixed constraint to the problem.
void	addGreaterThanConstraint(int[] i, double[] a, double b) Adds a new lower bounded constraint to the problem.
int	addIntegerVariable(double c) Adds a new Integer variable with the specified coefficient in the objective function to the problem.
void	addLessThanConstraint(int[] i, double[] a, double b) Adds a new upper bounded constraint to the problem.
int	addRealVariable(double c) Adds a new Real variable with the specified coefficient in the objective function to the problem.
boolean	getBooleanValue(int index) When the problem has been solved, use this method to retrieve the value of any Boolean inference variable.
int	getIntegerValue(int index) When the problem has been solved, use this method to retrieve the value of any Integer inference variable.
double	getRealValue(int index) When the problem has been solved, use this method to retrieve the value of any Real inference variable.
boolean	isSolved() Tests whether the problem represented by this ILPSolver instance has been solved already.
double	objectiveCoeff(int index) The coefficient of the variable in the objective function.
double	objectiveValue() When the problem has been solved, use this method to retrieve the value of the objective function at the solution.
void	printModelInfo()
void	reset() This method clears the all constraints and variables out of the ILP solver's problem representation, bringing the ILPSolver instance back to the state it was in when first constructed.
void	setBinary(int colId) Set the column / variable as an binary integer variable
void	setBounds(int colId, double lower, double upper) Set bounds of variable in the specified position.
void	setFloat(int colId) Set the column/variable as a float variable
void	setInteger(int colId) Set the column/variable as an integer variable
void	setLowerBound(int colId, double l)
void	setMaximize(boolean d) Sets the direction of the objective function.
void	setTimeout(int limit) Set a time limit for solver optimization.
void	setUnboundLowerBound(int colId) Set upper bound to unbounded (infinite)
void	setUnboundUpperBound(int colId) Set lower bound to unbounded (infinite)
void	setUpperBound(int colId, double u)
boolean	solve() Solves the ILP problem, saving the solution internally.
void	write(StringBuffer buffer) Creates a textual representation of the ILP problem in an algebraic notation.

Methods inherited from class java.lang.Object

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

Constructor Detail

OJalgoHook

public OJalgoHook()

Method Detail

setBounds

public void setBounds(int colId,
                      double lower,
                      double upper)

Set bounds of variable in the specified position.

Parameters:

colId - position of the variable

lower - domain lower bound

upper - domain upper bound

setUnboundUpperBound

public void setUnboundUpperBound(int colId)

Set lower bound to unbounded (infinite)

Parameters:

colId - position of the variable

setUpperBound

public void setUpperBound(int colId,
                          double u)

setUnboundLowerBound

public void setUnboundLowerBound(int colId)

Set upper bound to unbounded (infinite)

Parameters:

colId - position of the variable

setLowerBound

public void setLowerBound(int colId,
                          double l)

setInteger

public void setInteger(int colId)

Set the column/variable as an integer variable

Parameters:

colId - position of the variable

setBinary

public void setBinary(int colId)

Set the column / variable as an binary integer variable

Parameters:

colId - position of the variable

setFloat

public void setFloat(int colId)

Set the column/variable as a float variable

Parameters:

colId - position of the variable

setMaximize

public void setMaximize(boolean d)

Description copied from interface: ILPSolver

Sets the direction of the objective function.

Specified by:

setMaximize in interface ILPSolver

Parameters:

d - true if the objective function is to be maximized.

addBooleanVariable

public int addBooleanVariable(double c)

Description copied from interface: ILPSolver

Adds a new Boolean variable (an integer variable constrained to take either the value 0 or the value 1) with the specified coefficient in the objective function to the problem.

Specified by:

addBooleanVariable in interface ILPSolver

Parameters:

c - The objective function coefficient for the new Boolean variable.

Returns:

The indexes of the created variable.

addRealVariable

public int addRealVariable(double c)

Description copied from interface: ILPSolver

Adds a new Real variable with the specified coefficient in the objective function to the problem.

Specified by:

addRealVariable in interface ILPSolver

Parameters:

c - The objective function coefficient for the new Real variable.

Returns:

The indexes of the created variable.

addIntegerVariable

public int addIntegerVariable(double c)

Description copied from interface: ILPSolver

Adds a new Integer variable with the specified coefficient in the objective function to the problem.

Specified by:

addIntegerVariable in interface ILPSolver

Parameters:

c - The objective function coefficient for the new Integer variable.

Returns:

The indexes of the created variable.

addDiscreteVariable

public int[] addDiscreteVariable(double[] c)

Adds a general, multi-valued discrete variable, which is implemented as a set of Boolean variables, one per value of the discrete variable, with exactly one of those variables set true at any given time.

Specified by:

addDiscreteVariable in interface ILPSolver

Parameters:

c - The objective function coefficients for the new Boolean variables.

Returns:

The indexes of the newly created variables.

addEqualityConstraint

public void addEqualityConstraint(int[] i,
                                  double[] a,
                                  double b)

Description copied from interface: ILPSolver

Adds a new fixed constraint to the problem. The two array arguments must be the same length, as their elements correspond to each other. Variables whose coefficients are zero need not be mentioned. Variables that are mentioned must have previously been added via ILPSolver.addBooleanVariable(double) or ILPSolver.addDiscreteVariable(double[]). The resulting constraint has the form:

xi * a = b

where xi represents the inference variables whose indexes are contained in the array i and * represents dot product.

Specified by:

addEqualityConstraint in interface ILPSolver

Parameters:

i - The indexes of the variables with non-zero coefficients.

a - The coefficients of the variables with the given indexes.

b - The new constraint will enforce equality with this constant.

addGreaterThanConstraint

public void addGreaterThanConstraint(int[] i,
                                     double[] a,
                                     double b)

Description copied from interface: ILPSolver

Adds a new lower bounded constraint to the problem. The two array arguments must be the same length, as their elements correspond to each other. Variables whose coefficients are zero need not be mentioned. Variables that are mentioned must have previously been added via ILPSolver.addBooleanVariable(double) or ILPSolver.addDiscreteVariable(double[]). The resulting constraint has the form:

xi * a >= b

where xi represents the inference variables whose indexes are contained in the array i and * represents dot product.

Specified by:

addGreaterThanConstraint in interface ILPSolver

Parameters:

i - The indexes of the variables with non-zero coefficients.

a - The coefficients of the variables with the given indexes.

b - The lower bound for the new constraint.

addLessThanConstraint

public void addLessThanConstraint(int[] i,
                                  double[] a,
                                  double b)

Description copied from interface: ILPSolver

Adds a new upper bounded constraint to the problem. The two array arguments must be the same length, as their elements correspond to each other. Variables whose coefficients are zero need not be mentioned. Variables that are mentioned must have previously been added via ILPSolver.addBooleanVariable(double) or ILPSolver.addDiscreteVariable(double[]). The resulting constraint has the form:

xi * a <= b

where xi represents the inference variables whose indexes are contained in the array i and * represents dot product.

Specified by:

addLessThanConstraint in interface ILPSolver

Parameters:

i - The indexes of the variables with non-zero coefficients.

a - The coefficients of the variables with the given indexes.

b - The upper bound for the new constraint.

solve

public boolean solve()
              throws Exception

Description copied from interface: ILPSolver

Solves the ILP problem, saving the solution internally. This method may throw an exception if something doesn't go right.

Specified by:

solve in interface ILPSolver

Throws:

Exception

isSolved

public boolean isSolved()

Description copied from interface: ILPSolver

Tests whether the problem represented by this ILPSolver instance has been solved already.

Specified by:

isSolved in interface ILPSolver

getBooleanValue

public boolean getBooleanValue(int index)

Description copied from interface: ILPSolver

When the problem has been solved, use this method to retrieve the value of any Boolean inference variable. The result of this method is undefined when the problem has not yet been solved.

Specified by:

getBooleanValue in interface ILPSolver

Parameters:

index - The index of the variable whose value is requested.

Returns:

The value of the variable.

getRealValue

public double getRealValue(int index)

Description copied from interface: ILPSolver

When the problem has been solved, use this method to retrieve the value of any Real inference variable. The result of this method is undefined when the problem has not yet been solved.

Specified by:

getRealValue in interface ILPSolver

Parameters:

index - The index of the variable whose value is requested.

Returns:

The value of the variable.

getIntegerValue

public int getIntegerValue(int index)

Description copied from interface: ILPSolver

When the problem has been solved, use this method to retrieve the value of any Integer inference variable. The result of this method is undefined when the problem has not yet been solved.

Specified by:

getIntegerValue in interface ILPSolver

Parameters:

index - The index of the variable whose value is requested.

Returns:

The value of the variable.

objectiveValue

public double objectiveValue()

Description copied from interface: ILPSolver

When the problem has been solved, use this method to retrieve the value of the objective function at the solution. The result of this method is undefined when the problem has not yet been solved. If the problem had no feasible solutions, negative (positive, respectively) infinity will be returned if maximizing (minimizing).

Specified by:

objectiveValue in interface ILPSolver

Returns:

The value of the objective function at the solution.

objectiveCoeff

public double objectiveCoeff(int index)

Description copied from interface: ILPSolver

The coefficient of the variable in the objective function.

Specified by:

objectiveCoeff in interface ILPSolver

reset

public void reset()

Description copied from interface: ILPSolver

This method clears the all constraints and variables out of the ILP solver's problem representation, bringing the ILPSolver instance back to the state it was in when first constructed.

Specified by:

reset in interface ILPSolver

write

public void write(StringBuffer buffer)

Description copied from interface: ILPSolver

Creates a textual representation of the ILP problem in an algebraic notation.

Specified by:

write in interface ILPSolver

Parameters:

buffer - The created textual representation will be appended here.

setTimeout

public void setTimeout(int limit)

Set a time limit for solver optimization. After the limit is reached the solver stops running.

Parameters:

limit - the time limit

printModelInfo

public void printModelInfo()