在 for 循环期间计算运行总数 - Python

Calculate a running total during a for loop - Python

提问by tehaaron

Edit: Below is my working code based on the feedback/answers I recieved.

编辑：以下是我根据收到的反馈/答案编写的工作代码。

This question stems from my previous question that came up while learning Python/CS using open courseware from MIT. --See my previous question here--

这个问题源于我之前在使用 MIT 的开放课件学习 Python/CS 时提出的问题。--请在此处查看我之前的问题--

I am using the following code to make a list of month payments and other things. However at the end of the loop I need to give a running total for the total amount that has been paid of the months.

我正在使用以下代码来列出月付款和其他事项。但是，在循环结束时，我需要给出几个月已支付的总金额的运行总计。

Original Code

原始代码

balance = float(raw_input("Outstanding Balance: "))
interestRate = float(raw_input("Interest Rate: "))
minPayRate = float(raw_input("Minimum Monthly Payment Rate: "))

for month in xrange(1, 12+1):
    interestPaid = round(interestRate / 12.0 * balance, 2)
    minPayment = round(minPayRate * balance, 2)
    principalPaid = round(minPayment - interestPaid, 2)
    remainingBalance = round(balance - principalPaid, 2)


    print 'Month: %d' % (month,)
    print 'Minimum monthly payment: %.2f' % (minPayment,)
    print 'Principle paid: %.2f' % (principalPaid,)
    print 'Remaining balance: %.2f' % (remainingBalance,)

    balance = remainingBalance

    if month in xrange(12, 12+1):
        print 'RESULTS'
        print 'Total amount paid: '
        print 'Remaining balance: %.2f' % (remainingBalance,)

The problem is that I have not been able to figure out how to keep a running total of the amounts paid. I tried adding totalPaid = round(interestPaid + principalPaid, 2)but that just led to a total for a single month, I cant seem to get it to keep that value for each month and then add them all up at the end to be printed out.

问题是我一直无法弄清楚如何保持已支付金额的总和。我尝试添加，totalPaid = round(interestPaid + principalPaid, 2)但这只是导致一个月的总数，我似乎无法让它保持每个月的值，然后在最后将它们全部加起来以打印出来。

Also I know that the resulting amount should be 1131.12

我也知道结果金额应该是 1131.12

I have found many examples of doing this when each value is know, via a list, but I cant seem to extrapolate that correctly.

通过列表，我发现了许多在知道每个值时执行此操作的示例，但我似乎无法正确推断。

Fixed Code

固定码

balance = float(raw_input("Outstanding Balance: "))
interestRate = float(raw_input("Interest Rate: "))
minPayRate = float(raw_input("Minimum Monthly Payment Rate: "))
totalPaid = 0

for month in xrange(1, 12+1):
    interestPaid = round(interestRate / 12.0 * balance, 2)
    minPayment = round(minPayRate * balance, 2)
    principalPaid = round(minPayment - interestPaid, 2)
    remainingBalance = round(balance - principalPaid, 2)
    totalPaid += round(minPayment, 2)

    print 'Month: %d' % (month,)
    print 'Minimum monthly payment: %.2f' % (minPayment,)
    print 'Principle paid: %.2f' % (principalPaid,)
    print 'Remaining balance: %.2f' % (remainingBalance,)

    balance = remainingBalance

    if month in xrange(12, 12+1):
        print 'RESULTS'
        print 'Total amount paid: %.2f' % (totalPaid,)
        print 'Remaining balance: %.2f' % (remainingBalance,)

采纳答案by Rafe Kettler

Before your loop, initialize a variable to accumulate value:

在循环之前，初始化一个变量以累积值：

total_paid = 0

And then, in the body of your loop, add the appropriate amount to it. You can use the +=operator to add to an existing variable, e.g.

然后，在循环体中，添加适当的数量。您可以使用+=运算符添加到现有变量，例如

total_paid += 1

is a short form for total_paid = total_paid + 1. You don't want to give total_paida new value each iteration, rather you want to add to its existing value.

是 的缩写形式total_paid = total_paid + 1。您不希望total_paid每次迭代都赋予新值，而是希望添加到其现有值中。

I'm not sure about the specifics of your problem, but this is the general form for accumulating a value as you loop.

我不确定您的问题的具体情况，但这是在循环时累积值的一般形式。

回答by erKURITA

You actually have to initialize totalPaid to 0 and then

您实际上必须将 totalPaid 初始化为 0 然后

totalPaid = round(interestPaid + principalPaid, 2) + totalPaid

Inside the loop. Your problem is that you're not accumulating the total, you're just setting a new one on each iteration.

圈内。你的问题是你没有累积总数，你只是在每次迭代中设置一个新的。

回答by GSto

sounds like you were close. The problem is that you were overwriting the total each time. Try something like this:

听起来你很接近。问题是你每次都覆盖总数。尝试这样的事情：

totalPaid = totalPaid + round(interestPaid + principalPaid, 2)

回答by Fred Nurk

You always make the minimum payment? Just use minPayment instead of figuring out that math again. Keep a running total, then print it out afterthe loop.

你总是支付最低还款额？只需使用 minPayment 而不是再次计算该数学。保持运行总数，然后在循环后打印出来。

balance = float(raw_input("Outstanding Balance: "))
interestRate = float(raw_input("Interest Rate: "))
minPayRate = float(raw_input("Minimum Monthly Payment Rate: "))
paid = 0

for month in xrange(1, 12+1):
    interestPaid = round(interestRate / 12.0 * balance, 2)
    minPayment = round(minPayRate * balance, 2)
    principalPaid = round(minPayment - interestPaid, 2)
    remainingBalance = round(balance - principalPaid, 2)
    paid += minPayment

    print  # Make the output easier to read.
    print 'Month: %d' % (month,)
    print 'Minimum monthly payment: %.2f' % (minPayment,)
    print 'Principle paid: %.2f' % (principalPaid,)
    print 'Remaining balance: %.2f' % (remainingBalance,)

    balance = remainingBalance

print
print 'RESULTS'
print 'Total amount paid:', paid
print 'Remaining balance: %.2f' % (remainingBalance,)

Also notice that range has exactly one value, so you'd just check month == 12, but it's simply not necessary here.

另请注意，范围只有一个值，因此您只需检查月 == 12，但在这里根本没有必要。