__init__(self, solver=None)
(Constructor)

Parameters:

solver - Problem solver used to find solutions (default is BacktrackingSolver)
           (type=instance of a Solver subclass)

Overrides:

__builtin__.object.__init__

addConstraint(self, constraint, variables=None)

Add a constraint to the problem

>>> problem = Problem()
>>> problem.addVariables(["a", "b"], [1, 2, 3])
>>> problem.addConstraint(lambda a, b: b == a+1, ["a", "b"])
>>> solutions = problem.getSolutions()
>>>

Parameters:

constraint - Constraint to be included in the problem
           (type=instance a Constraint subclass or a function to be wrapped by FunctionConstraint)

variables - Variables affected by the constraint (default to all variables). Depending on the constraint type the order may be important.
           (type=set or sequence of variables)

addVariable(self, variable, domain)

Add a variable to the problem

>>> problem = Problem()
>>> problem.addVariable("a", [1, 2])
>>> problem.getSolution() in ({'a': 1}, {'a': 2})
True

Parameters:

variable - Object representing a problem variable
           (type=hashable object)

domain - Set of items defining the possible values that the given variable may assume
           (type=list, tuple, or instance of Domain)

addVariables(self, variables, domain)

Add one or more variables to the problem

>>> problem = Problem()
>>> problem.addVariables(["a", "b"], [1, 2, 3])
>>> solutions = problem.getSolutions()
>>> len(solutions)
9

>>> {'a': 3, 'b': 1} in solutions
True

Parameters:

variables - Any object containing a sequence of objects represeting problem variables
           (type=sequence of hashable objects)

domain - Set of items defining the possible values that the given variables may assume
           (type=list, tuple, or instance of Domain)

getSolution(self)

Find and return a solution to the problem

>>> problem = Problem()
>>> problem.getSolution() is None
True

>>> problem.addVariables(["a"], [42])
>>> problem.getSolution()
{'a': 42}

Returns:

Solution for the problem
           (type=dictionary mapping variables to values)

getSolutionIter(self)

Return an iterator to the solutions of the problem

>>> problem = Problem()
>>> list(problem.getSolutionIter()) == []
True

>>> problem.addVariables(["a"], [42])
>>> iter = problem.getSolutionIter()
>>> iter.next()
{'a': 42}

>>> iter.next()
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
StopIteration

getSolutions(self)

Find and return all solutions to the problem

>>> problem = Problem()
>>> problem.getSolutions() == []
True

>>> problem.addVariables(["a"], [42])
>>> problem.getSolutions()
[{'a': 42}]

Returns:

All solutions for the problem
           (type=list of dictionaries mapping variables to values)

getSolver(self)

Obtain the problem solver currently in use

>>> solver = BacktrackingSolver()
>>> problem = Problem(solver)
>>> problem.getSolver() is solver
True

Returns:

Solver currently in use
           (type=instance of a Solver subclass)

reset(self)

Reset the current problem definition

>>> problem = Problem()
>>> problem.addVariable("a", [1, 2])
>>> problem.reset()
>>> problem.getSolution()
>>>

setSolver(self, solver)

Change the problem solver currently in use

>>> solver = BacktrackingSolver()
>>> problem = Problem(solver)
>>> problem.getSolver() is solver
True

Parameters:

solver - New problem solver
           (type=instance of a Solver subclass)