class ElectricCircuit:

def __init__(self, voltage=None, current=None, resistance=None):"""Args:voltage (float): 电压值，默认为None。current (float): 电流值，默认为None。resistance (float): 电阻值，默认为None。"""self.voltage = voltageself.current = currentself.resistance = resistancedef calculate_voltage(self, current):"""计算电压值。Args:current (float): 电流值，单位为安培。Returns:float: 电压值，单位为伏特。Raises:ValueError: 当电路中没有设置电阻时抛出异常。"""if self.resistance is None:raise ValueError("Resistance is not set in the circuit.")return current * self.resistancedef calculate_current(self, voltage):"""计算电流值。Args:voltage (float): 电压值。Returns:float: 电流值。Raises:ValueError: 当电路中的电阻值为None时，抛出异常。"""if self.resistance is None:raise ValueError("Resistance is not set in the circuit.")return voltage / self.resistance"""计算电路中的电压。Args:current (float): 电流值。Returns:float: 电压值。Raises:ValueError: 如果电路中没有设置电阻，则抛出此异常。"""def calculate_resistance(self):"""计算电阻。Args:无。Returns:float: 计算得到的电阻值。Raises:ValueError: 如果电压或电流未设置，则抛出此异常。"""if self.voltage is None or self.current is None:raise ValueError("Both voltage and current should be set to calculate resistance.")return self.voltage / self.current

#分别求出电阻，电压，电流，使用条件判断

circuit = ElectricCircuit(voltage=12, current=2)
vol=circuit.voltage
cur=circuit.current
resistance = circuit.calculate_resistance()
print(‘-’*30)
print(f"\n单个电阻电路中，求电阻\n\n 解:电压U={vol}V,电流I={cur}A,本题电阻R={resistance} Ω.\n")

circuit = ElectricCircuit(voltage=12, resistance=4)
vol = circuit.voltage
res = circuit.resistance
current = circuit.calculate_current(vol)
print(‘-’*30)
print(f"单个电阻电路中，求电流\n\n 解:电压U={vol}V,电阻R={res}Ω,本题电流I={current}A.\n")

circuit = ElectricCircuit(current=2, resistance=4)
cur = circuit.current
res = circuit.resistance
voltage = circuit.calculate_voltage(cur)
print(‘-’*30)
print(f"单个电阻电路中，求电压\n\n 解:电流I={cur}A,电阻R={res}Ω,本题电压U={voltage}V.\n")