def setUp(self):
ii = 10
self.steps = 6
pairs = [(1.0, 0.5), (0.7, 1.0), (0.5, 1.5), (0.3, 2.5)]
self.cp: ClearancePricingMDP = ClearancePricingMDP(
initial_inventory=ii,
time_steps=self.steps,
price_lambda_pairs=pairs)
def policy_func(x: int) -> int:
return 0 if x < 2 else (1 if x < 5 else (2 if x < 8 else 3))
stationary_policy: FiniteDeterministicPolicy[int, int] = \
FiniteDeterministicPolicy(
{s: policy_func(s) for s in range(ii + 1)}
)
self.single_step_mrp: FiniteMarkovRewardProcess[int] = \
self.cp.single_step_mdp.apply_finite_policy(stationary_policy)
self.mrp_seq = unwrap_finite_horizon_MRP(
finite_horizon_MRP(self.single_step_mrp, self.steps))
self.single_step_mdp: FiniteMarkovDecisionProcess[int, int] = \
self.cp.single_step_mdp
self.mdp_seq = unwrap_finite_horizon_MDP(
finite_horizon_MDP(self.single_step_mdp, self.steps))
def get_vf_for_policy(
self,
policy: FinitePolicy[WithTime[int], int]
) -> Iterator[V[int]]:
mrp: FiniteMarkovRewardProcess[WithTime[int]] \
= self.mdp.apply_finite_policy(policy)
return evaluate(unwrap_finite_horizon_MRP(mrp), 1.)
def test_evaluate(self):
process = finite_horizon_MRP(self.finite_flip_flop, 10)
vs = list(evaluate(unwrap_finite_horizon_MRP(process), gamma=1))
self.assertEqual(len(vs), 10)
self.assertAlmostEqual(vs[0][NonTerminal(True)], 17)
self.assertAlmostEqual(vs[0][NonTerminal(False)], 17)
self.assertAlmostEqual(vs[5][NonTerminal(True)], 17 / 2)
self.assertAlmostEqual(vs[5][NonTerminal(False)], 17 / 2)
self.assertAlmostEqual(vs[9][NonTerminal(True)], 17 / 10)
self.assertAlmostEqual(vs[9][NonTerminal(False)], 17 / 10)
def test_compare_to_backward_induction(self):
finite_horizon = finite_horizon_MRP(self.finite_flip_flop, 10)
v = evaluate_mrp_result(finite_horizon, gamma=1)
self.assertEqual(len(v), 20)
finite_v =\
list(evaluate(unwrap_finite_horizon_MRP(finite_horizon), gamma=1))
for time in range(0, 10):
self.assertAlmostEqual(v[WithTime(state=True, time=time)],
finite_v[time][True])
self.assertAlmostEqual(v[WithTime(state=False, time=time)],
finite_v[time][False])
def test_compare_to_backward_induction(self):
finite_horizon = finite_horizon_MRP(self.finite_flip_flop, 10)
start = Dynamic({s: 0.0 for s in finite_horizon.states()})
v = FunctionApprox.converged(
evaluate_finite_mrp(finite_horizon, γ=1, approx_0=start))
self.assertEqual(len(v.values_map), 22)
finite_v =\
list(evaluate(unwrap_finite_horizon_MRP(finite_horizon), gamma=1))
for time in range(0, 10):
self.assertAlmostEqual(v(WithTime(state=True, time=time)),
finite_v[time][True])
self.assertAlmostEqual(v(WithTime(state=False, time=time)),
finite_v[time][False])
def test_unwrap_finite_horizon_MRP(self):
finite = finite_horizon_MRP(self.finite_flip_flop, 10)
def transition_for(_):
return {
True: Categorical({
(NonTerminal(True), 1.0): 0.3,
(NonTerminal(False), 2.0): 0.7
}),
False: Categorical({
(NonTerminal(True), 2.0): 0.7,
(NonTerminal(False), 1.0): 0.3
})
}
unwrapped = unwrap_finite_horizon_MRP(finite)
self.assertEqual(len(unwrapped), 10)
expected_transitions = [transition_for(n) for n in range(10)]
for time in range(9):
got = unwrapped[time]
expected = expected_transitions[time]
distribution.assert_almost_equal(
self, got[NonTerminal(True)],
expected[True]
)
distribution.assert_almost_equal(
self, got[NonTerminal(False)],
expected[False]
)
distribution.assert_almost_equal(
self, unwrapped[9][NonTerminal(True)],
Categorical({
(Terminal(True), 1.0): 0.3,
(Terminal(False), 2.0): 0.7
})
)
distribution.assert_almost_equal(
self, unwrapped[9][NonTerminal(False)],
Categorical({
(Terminal(True), 2.0): 0.7,
(Terminal(False), 1.0): 0.3
})
)
def test_unwrap_finite_horizon_MRP(self):
finite = finite_horizon_MRP(self.finite_flip_flop, 10)
def transition_for(time):
return {
True: Categorical({
(True, 1.0): 0.3,
(False, 2.0): 0.7,
}),
False: Categorical({
(True, 2.0): 0.7,
(False, 1.0): 0.3,
})
}
unwrapped = unwrap_finite_horizon_MRP(finite)
self.assertEqual(len(unwrapped), 10)
expected_transitions = [transition_for(n) for n in range(0, 10)]
for time in range(0, 10):
got = unwrapped[time]
expected = expected_transitions[time]
distribution.assert_almost_equal(self, got[True], expected[True])
distribution.assert_almost_equal(self, got[False], expected[False])
print("Clearance Pricing MDP")
print("---------------------")
print(cp.mdp)
def policy_func(x: int) -> int:
return 0 if x < 2 else (1 if x < 5 else (2 if x < 8 else 3))
stationary_policy: FinitePolicy[int, int] = FinitePolicy(
{s: Constant(policy_func(s)) for s in range(ii + 1)}
)
single_step_mrp: FiniteMarkovRewardProcess[int] = \
cp.single_step_mdp.apply_finite_policy(stationary_policy)
vf_for_policy: Iterator[V[int]] = evaluate(
unwrap_finite_horizon_MRP(finite_horizon_MRP(single_step_mrp, steps)),
1.
)
print("Value Function for Stationary Policy")
print("------------------------------------")
for t, vf in enumerate(vf_for_policy):
print(f"Time Step {t:d}")
print("---------------")
pprint(vf)
print("Optimal Value Function and Optimal Policy")
print("------------------------------------")
prices = []
for t, (vf, policy) in enumerate(cp.get_optimal_vf_and_policy()):
print(f"Time Step {t:d}")