def test_forwardcheck_empty_domain():
constrainer = SomeNotInSetConstraint(set('abc'))
v1, v2 = variables = [Variable('v1'), Variable('v2')]
domains = {v1: Domain(['a']), v2: Domain(['b'])}
assert constrainer(variables, domains, {v1: 'a'})
assert not constrainer(variables, domains, {v1: 'a'}, True)
def preProcess(self, variables, domains, constraints, vconstraints):
if 'edge_tag_cache' not in self.graph.graph:
return
cache = self.graph.graph['edge_tag_cache']
if self.tag not in cache:
edges = []
e_0 = set()
e_1 = set()
for i, j, t in self.graph.edges(data="tag"):
if t == self.tag:
e_0.add(i)
e_1.add(j)
edges.append((i, j))
cache[self.tag] = edges
else:
# FIXME: would it be better to switch to representing edges as
# edge variables, instead of a pair of node variables?
edges = cache[self.tag]
e_0 = set(e[0] for e in edges)
e_1 = set(e[1] for e in edges)
vb = iter(variables)
for i, j in zip(vb, vb):
if self.graph.is_directed():
domains[i] = Domain(e_0)
domains[j] = Domain(e_1)
else:
all_nodes = e_0.union(e_1)
domains[i] = Domain(all_nodes)
domains[j] = Domain(all_nodes)
def preProcess(self, variables, domains, constraints, vconstraints):
# If only a single variable allowed, variables must be equal to that.
# If domain already chopped, then what?
if len(self.allowedSet) == 0:
# Impossible
for v in variables:
domains[v] = Domain([])
vconstraints[v].remove((self, variables))
constraints.remove((self, variables))
return
elif len(self.allowedSet) == 1:
allowed = next(iter(self.allowedSet))
for (v, val) in zip(variables, allowed):
if val in domains[v]:
domains[v] = Domain([val])
else:
domains[v] = Domain([])
vconstraints[v].remove((self, variables))
constraints.remove((self, variables))
return
# If some variable is only allowed a subset of values in its domain,
# then restrict to that subset.
for (i, v) in enumerate(variables):
allowed = set(domains[v]).intersection(self.nthSet[i])
domains[v] = Domain(list(allowed))
def test_forwardcheck_empty_domain():
constrainer = SomeNotInSetConstraint(set("abc"))
v1, v2 = variables = [Variable("v1"), Variable("v2")]
domains = {v1: Domain(["a"]), v2: Domain(["b"])}
assert constrainer(variables, domains, {v1: "a"})
assert not constrainer(variables, domains, {v1: "a"}, True)
def test_forwardcheck():
constrainer = SomeNotInSetConstraint(set('abc'), n=2)
v1, v2, v3 = variables = [Variable('v1'), Variable('v2'), Variable('v3')]
domains = {v1: Domain(['a']), v2: Domain(['b', 'y']),
v3: Domain(['c', 'z'])}
assert constrainer(variables, domains, {v1: 'a'})
assert ['a'] == list(domains[v1])
assert ['b', 'y'] == list(domains[v2])
assert ['c', 'z'] == list(domains[v3])
assert constrainer(variables, domains, {v1: 'a'}, True)
assert ['a'] == list(domains[v1])
assert ['y'] == list(domains[v2])
assert ['z'] == list(domains[v3])
def test_forwardcheck():
constrainer = SomeNotInSetConstraint(set("abc"), n=2)
v1, v2, v3 = variables = [Variable("v1"), Variable("v2"), Variable("v3")]
domains = {
v1: Domain(["a"]),
v2: Domain(["b", "y"]),
v3: Domain(["c", "z"])
}
assert constrainer(variables, domains, {v1: "a"})
assert ["a"] == list(domains[v1])
assert ["b", "y"] == list(domains[v2])
assert ["c", "z"] == list(domains[v3])
assert constrainer(variables, domains, {v1: "a"}, True)
assert ["a"] == list(domains[v1])
assert ["y"] == list(domains[v2])
assert ["z"] == list(domains[v3])
def preProcess(self, variables, domains, constraints, vconstraints):
if 'node_tag_cache' not in self.graph.graph:
return
cache = self.graph.graph['node_tag_cache']
if self.tag not in cache:
nodes = []
for n, t in self.graph.nodes(data="tag"):
if t == self.tag:
nodes.append(n)
cache[self.tag] = nodes
else:
nodes = cache[self.tag]
for v in variables:
domains[v] = Domain(nodes)
def test_forwardcheck_exact():
constrainer = SomeNotInSetConstraint(set('abc'), n=2, exact=True)
v1, v2, v3 = variables = [Variable('v1'), Variable('v2'), Variable('v3')]
assignments = {v1: 'a'}
domains = {v1: Domain(['a', 'x']), v2: Domain(['b', 'y']),
v3: Domain(['c', 'z'])}
assert constrainer(variables, domains, assignments)
assert constrainer(variables, domains, assignments, True)
assert 'b' not in domains[v2]
assert 'y' in domains[v2]
assert 'c' not in domains[v3]
assert 'z' in domains[v3]
domains = {v1: Domain(['a', 'x']), v2: Domain(['b', 'y']),
v3: Domain(['c'])}
assert constrainer(variables, domains, assignments)
assert not constrainer(variables, domains, assignments, True)
def test_forwardcheck_exact():
constrainer = SomeNotInSetConstraint(set("abc"), n=2, exact=True)
v1, v2, v3 = variables = [Variable("v1"), Variable("v2"), Variable("v3")]
assignments = {v1: "a"}
domains = {
v1: Domain(["a", "x"]),
v2: Domain(["b", "y"]),
v3: Domain(["c", "z"])
}
assert constrainer(variables, domains, assignments)
assert constrainer(variables, domains, assignments, True)
assert "b" not in domains[v2]
assert "y" in domains[v2]
assert "c" not in domains[v3]
assert "z" in domains[v3]
domains = {
v1: Domain(["a", "x"]),
v2: Domain(["b", "y"]),
v3: Domain(["c"])
}
assert constrainer(variables, domains, assignments)
assert not constrainer(variables, domains, assignments, True)