def __init__(self, free_sections_only=True, problem=None, constraint=None):
self.p = Problem()
if problem is not None:
self.p = problem
self.free_sections_only = free_sections_only
self.section_constraint = constraint or section_constraint
self.clear_excluded_times()
class Scheduler(object):
"""High-level API that wraps the course scheduling feature.
``free_sections_only``: bool. Determines if the only the available sections should be
used when using courses provided. Defaults to True.
``problem``: Optional problem instance to provide. If None, the default one is created.
"""
def __init__(self, free_sections_only=True, problem=None):
self.p = Problem()
if problem is not None:
self.p = problem
self.free_sections_only = free_sections_only
self.clear_excluded_times()
def clear_excluded_times(self):
"""Clears all previously set excluded times."""
self._excluded_times = []
return self
def exclude_time(self, start, end, days):
"""Added an excluded time by start, end times and the days.
``start`` and ``end`` are in military integer times (e.g. - 1200 1430).
``days`` is a collection of integers or strings of fully-spelt, lowercased days
of the week.
"""
self._excluded_times.append(TimeRange(start, end, days))
return self
def exclude_times(self, *tuples):
"""Adds multiple excluded times by tuple of (start, end, days) or by
TimeRange instance.
``start`` and ``end`` are in military integer times (e.g. - 1200 1430).
``days`` is a collection of integers or strings of fully-spelt, lowercased days
of the week.
"""
for item in tuples:
if isinstance(item, TimeRange):
self._excluded_times.append(item)
else:
self.exclude_time(*item)
return self
def find_schedules(self, courses=None, generator=False, start=0):
"""Returns all the possible course combinations. Assumes no duplicate courses.
``return_generator``: If True, returns a generator instead of collection. Generators
are friendlier to your memory and save computation time if not all solutions are
used.
"""
self.p.reset()
self.create_variables(courses)
self.create_constraints(courses)
self.p.restore_point(start)
if generator:
return self.p.iter_solutions()
return self.p.get_solutions()
# internal methods -- can be overriden for custom use.
def get_sections(self, course):
"""Internal use. Returns the sections to use for the solver for a given course.
"""
return course.available_sections if self.free_sections_only else course.sections
def time_conflict(self, schedule):
"""Internal use. Determines when the given time range conflicts with the set of
excluded time ranges.
"""
for timerange in self._excluded_times:
if timerange.conflicts_with(schedule):
return False
return True
def create_variables(self, courses):
"""Internal use. Creates all variables in the problem instance for the given
courses. If given a dict of {course: sections}, will use the provided sections.
"""
has_sections = isinstance(courses, dict)
for course in courses:
self.p.add_variable(course, courses.get(course, []) if has_sections else self.get_sections(course))
def create_constraints(self, courses):
"""Internal use. Creates all constraints in the problem instance for the given
courses.
"""
for i, course1 in enumerate(courses):
for j, course2 in enumerate(courses):
if i <= j:
continue
self.p.add_constraint(section_constraint, [course1, course2])
self.p.add_constraint(self.time_conflict, [course1])
from csp import Problem
p = Problem()
pvars = "R2 R3 R5 R6 R7 R8 R9 R10 X Y Z".split()
# 0-151 is the possible finite range of the variables
p.addvars(pvars, xrange(152))
p.addrule("R7 == X + 11")
p.addrule("R8 == Y + 11")
p.addrule("R9 == Y + 4")
p.addrule("R10 == Z + 4")
p.addrule("R7 + R8 == 40")
p.addrule("R5 == R8 + R9")
p.addrule("R6 == R9 + R10")
p.addrule("R2 == 40 + R5")
p.addrule("R3 == R5 + R6")
p.addrule("R2 + R3 == 151")
p.addrule("Y == X + Z")
for sol in p.xsolutions():
print[sol[k] for k in "XYZ"]
def setUp(self):
self.p = Problem(BacktrackingSolver())
self.p.add_variable('x', range(3))
self.p.add_variable('y', range(3))
class PointConstaintIntegrationTestForBacktracker(unittest.TestCase):
def setUp(self):
self.p = Problem(BacktrackingSolver())
self.p.add_variable('x', range(3))
self.p.add_variable('y', range(3))
def result(self, *iter):
return tuple(dict(x=x, y=y) for x, y in iter)
def test_reset_problem(self):
result1 = self.p.get_solutions()
self.p.reset()
self.p.add_variable('x', range(3))
self.p.add_variable('y', range(3))
result2 = self.p.get_solutions()
self.assertEqual(result1, result2)
def test_save_and_restore_iteration_position(self):
it = self.p.iter_solutions()
next(it)
ref = self.p.save_point()
second_answer = next(it)
self.p.reset()
self.p.add_variable('x', range(3))
self.p.add_variable('y', range(3))
self.p.restore_point(ref)
answer = next(self.p.iter_solutions())
self.assertEqual(second_answer, answer)
def test_with_no_constraints_should_have_all_permutations(self):
#self.p.add_constraint(lambda x, y: x != y, ['x', 'y'])
expected = self.result((0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2))
assertEqualContents(self.p.get_solutions(), expected)
def test_should_have_non_equal_permutations(self):
expected = self.result((0, 1), (0, 2), (1, 0), (1, 2), (2, 0), (2, 1))
self.p.add_constraint(lambda x, y: x != y, ['x', 'y'])
assertEqualContents(self.p.get_solutions(), expected)
def test_should_have_non_equal_permutations_or_sum_to_3(self):
expected = self.result((0, 1), (0, 2), (1, 0), (2, 0))
self.p.add_constraint(lambda x, y: x != y, ['x', 'y'])
self.p.add_constraint(lambda x, y: x + y != 3, ['x', 'y'], [0, 0])
assertEqualContents(self.p.get_solutions(), expected)
def test_should_have_non_equal_permutations_while_x_is_lte_1(self):
expected = self.result((0, 1), (0, 2), (1, 0), (1, 2))
self.p.add_constraint(lambda x, y: x != y, ['x', 'y'])
self.p.add_constraint(lambda x: x <= 1, ['x'], [0])
assertEqualContents(self.p.get_solutions(), expected)
def setUp(self):
self.p = Problem(BruteForceSolver())
self.p.add_variable('x', range(3))
self.p.add_variable('y', range(3))
