def __init__(self, quantity, time_unit='Y'):
Validate.required(quantity, "quantity")
Validate.non_negative(quantity, "quantity")
self.quantity = quantity
Validate.one_of_allowable(time_unit, ['Y', 'M', 'W', 'D'], "time_unit")
self.time_unit = time_unit
def shortage_cost(shortage_cost, shortage_quantity):
"""
Calculate the shortage cost - the total cost of not having units in stock,
including costs due to backorder, lost sales, lost customers, and operational
disruptions.
Parameters
----------
shortage_cost : int or float
Cost per unit of shortage, in dollars
shortage_quantity : int
The number of units of shortage, in units
Returns
-------
shortage_cost : float
"""
Validate.required(shortage_cost, "shortage_cost")
Validate.non_negative(shortage_cost, "shortage_cost")
Validate.required(shortage_quantity, "shortage_quantity")
Validate.non_negative(shortage_quantity, "shortage_quantity")
return shortage_cost * shortage_quantity
def ordering_cost(ordering_cost, demand_quantity, order_quantity):
"""
Calculate the ordering cost - the total cost of placing, receiving,
and processing orders needed to fulfill a given amount of demand.
Parameters
----------
ordering_cost : int or float
Cost per order, in dollars
demand_quantity : int
The amount of demand, in units
order_quantity : int
The number of units purchased per order, in units
Returns
-------
ordering_cost: float
"""
Validate.required(ordering_cost, "ordering_cost")
Validate.non_negative(ordering_cost, "ordering_cost")
Validate.required(demand_quantity, "demand_quantity")
Validate.non_negative(demand_quantity, "demand_quantity")
Validate.required(order_quantity, "order_quantity")
Validate.positive(order_quantity, "order_quantity")
return ordering_cost * (demand_quantity / order_quantity)
def validate_init_values(unit_cost, ordering_cost, holding_rate,
holding_cost, holding_time_unit, shortage_cost):
Validate.required(unit_cost, "unit_cost")
Validate.non_negative(unit_cost, "unit_cost")
Validate.required(ordering_cost, "ordering_cost")
Validate.non_negative(ordering_cost, "ordering_cost")
# accept holding_rate or holding_cost, but not both
# (at least one is required)
Validate.one_only([holding_rate, holding_cost],
["holding_rate", "holding_cost"])
if holding_rate is not None:
Validate.non_negative(holding_rate, "holding_rate")
else:
Validate.non_negative(holding_cost, holding_cost)
Validate.one_of_allowable(holding_time_unit,
RawCosts.supported_time_units,
"holding_time_unit")
Validate.required(shortage_cost, "shortage_cost")
Validate.non_negative(shortage_cost, "shortage_cost")
def holding_cost(holding_cost, order_quantity):
"""
Calculate the holding cost - the total cost of holding excess inventory,
including storage, service costs, risk costs, and capital costs.
Parameters
----------
holding_cost : int or float
Cost per unit of inventory per time period, in dollars
order_quantity : int
The number of units purchased per order, in units
Returns
-------
holding_cost: float
"""
Validate.required(holding_cost, "holding_cost")
Validate.non_negative(holding_cost, "holding_cost")
Validate.required(order_quantity, "order_quantity")
Validate.non_negative(order_quantity, "order_quantity")
return holding_cost * (order_quantity / 2)
def purchase_cost(unit_cost, demand_quantity):
"""
Calculate the purchase cost - the total landed cost for acquiring
product needed to satisfy a given amount of demand.
Parameters
----------
unit_cost : int or float
Cost per unit, in dollars
demand_quantity : int
The amount of demand, in units
Returns
-------
purchase_cost: float
"""
Validate.required(unit_cost, "unit_cost")
Validate.non_negative(unit_cost, "unit_cost")
Validate.required(demand_quantity, "demand_quantity")
Validate.non_negative(demand_quantity, "demand_quantity")
return unit_cost * demand_quantity
