def update(self, time, current_state, next_state):
""" updates the discounted total cost and health utility
:param time: simulation time
:param current_state: current health state
:param next_state: next health state
"""
# cost and utility (per unit of time) during the period since the last recording until now
cost = self.params.annualStateCosts[
current_state.value] + self.params.annualTreatmentCost
utility = self.params.annualStateUtilities[current_state.value]
# discounted cost and utility (continuously compounded)
discounted_cost = Econ.pv_continuous_payment(
payment=cost,
discount_rate=self.params.discountRate,
discount_period=(self.tLastRecorded, time))
discounted_utility = Econ.pv_continuous_payment(
payment=utility,
discount_rate=self.params.discountRate,
discount_period=(self.tLastRecorded, time))
# update total discounted cost and utility
self.totalDiscountedCost += discounted_cost
self.totalDiscountedUtility += discounted_utility
# update the time since last recording to the current time
self.tLastRecorded = time
def update(self, time, current_state, next_state):
# cost (per unit of time) during the period since the last recording until now
cost = self.params.annualStateCosts[current_state.value]
if current_state == HealthStates.POST_STROKE:
cost += self.params.annuaAntiCoagCost
# discounted cost and utility (continuously compounded)
discounted_cost = Econ.pv_continuous_payment(payment=cost,
discount_rate=self.params.discountRate,
discount_period=(self.tLastRecorded, time))
# add discounted stoke cost, if stroke occurred
if next_state == HealthStates.STROKE:
discounted_cost += Econ.pv_single_payment(payment=self.params.strokeCost,
discount_rate=self.params.discountRate,
discount_period=time,
discount_continuously=True)
# utility (per unit of time) during the period since the last recording until now
utility = self.params.annualStateUtilities[current_state.value]
discounted_utility = Econ.pv_continuous_payment(payment=utility,
discount_rate=self.params.discountRate,
discount_period=(self.tLastRecorded, time))
# update total discounted cost and utility
self.totalDiscountedCost += discounted_cost
self.totalDiscountedUtility += discounted_utility
# update the time since last recording to the current time
self.tLastRecorded = time
import SimPy.EconEval as Econ
print('Present value of $10 collected in year 20 at discount rate 5%:')
print(Econ.pv_single_payment(payment=10, discount_rate=0.05, discount_period=20))
print('\nPresent value of $10 collected in year 20 at discount rate 5% (discounted continuously):')
print('These 2 numbers should be almost the same:')
print(Econ.pv_single_payment(payment=10, discount_rate=0.05,
discount_period=20, discount_continuously=True))
print(Econ.pv_single_payment(payment=10, discount_rate=0.05 / 100,
discount_period=20 * 100, discount_continuously=False))
print('\nPresent value of a continuous payment of $10 over the period [10, 20] at discount rate 5%:')
print(Econ.pv_continuous_payment(payment=10, discount_rate=0.05, discount_period=(10, 20)))
print('\nPresent value of a continuous payment of $10 over the period [10, 20] at discount rate 0%:')
print(Econ.pv_continuous_payment(payment=10, discount_rate=0, discount_period=(10, 20)))
print('\nEquivalent annual value of $50 over 10 years at discount rate 5%:')
print(Econ.equivalent_annual_value(present_value=50, discount_rate=0.05, discount_period=10))