如何在python中正确调用我的函数？

Question

我的def main()部分遇到了问题，特别是当我调用循环其他变量时。

我检查了我的参数是否检查，他们做了什么。当我评论该部分时，代码“工作”，并且它不会崩溃。但是，当取消注释时，它会一直说在分配之前引用了我的fileInput变量。

然后我尝试将fileIn中的def readFile()切换到if yearIn == 2008之前，但现在错误显示了预期的字符串值（我没有“”我的因为我希望它是一个整数）。

我究竟做错了什么？我希望我的代码能够运行并输出一个文件，列出具有最高和最低MPG的汽车。

def readFile(yearIn):

    # open file
    if yearIn == 2008:
        fileInput = open("epaVehicleData2008.csv", "r")
    else:
        fileInput = open("epaVehicleData2009.csv", "r")

    fileIn = open(fileInput, "r")

    # open file
    # if yearIn == 2008:
    #     fileInput = open("epaVehicleData2008.csv", "r")
    # else:
    #     fileInput = open("epaVehicleData2009.csv", "r")

    count = 0

    #empty list
    manufactureList =[]
    carTypeList = []
    mpgList = []


    for line in fileIn:
        line = line.strip()
        carInfo = line.split(",")
        if count != 0:
            if "VAN" not in carInfo[0] and "PICKUP" not in carInfo[0] and "CLASS" not in carInfo[0]:
                manufactureList(carInfo[1])
                carTypeList(carInfo[2])
                mpgList.append(carInfo[9])
        count += 1

    maxMPG = max(mpgList)
    minMPG = min(mpgList)

    minCars = []
    maxCars = []

    for X in range(len(mpgList)):
        if mpgList[X] == minMPG:
            result = manufactureList[X] + " " + carTypeList[X]
            minMPG.append(result)

        if mpgList[X] == maxMPG:
            result = manufactureList[X] + " " + carTypeList[X]
            maxCars.append(result)

    #close
    fileIn.close()

    return maxMPG, minMPG, maxCar, minCar



def writeFile(fileName, year, maxMPG, minMPG, maxCar, minCar):

    #open file
    fileOut = open(fileName, "w")

    print("EPA Highway MPG Calculator", year, file = fileOut)
    print("-----------------------------------")
    print("Maximum Mileage (highway):", maxMPG, file=fileOut)
    print("\n".join(maxCars), file=fileOut)

    print("Minimum Mileage (highway):", minMPG, file=fileOut)
    print("\n".join(minCar), file=fileOut)

    #close file
    fileOut.close()


def main():

    print("Welcome to EPA Mileage Calculator.")

    #user select year
    yearIn = int(input("What year would you like to view data for (2008 or 2009)? "))

    #invalid input if neither 2008/2009
    while yearIn != 2008 and yearIn != 2009:
        print("Invalid input, please try again.")
        yearIn = int(input("What year would you like to view data for (2008 or 2009)? "))

    fileNameSave = input("Enter the filename to save results to (.txt file): ")
    print("Operation Success! Mileage data has been saved to", fileNameSave)
    print("Goodbye.")


    maxMPG, minMPG, maxCar, minCar = readFile(yearIn)

    #minMPG = readFile(yearIn)
    #carTypeList = readFile(yearIn)
    #manufactureList = readFile(yearIn)

    writeFile(fileNameSave, yearIn, maxMPG, minMPG, maxCar, minCar) 

main()