在for循环中计算运行总数 - Python [英] Calculate a running total during a for loop - Python

问题描述

编辑：下面是我的工作代码基于我收到的反馈/答案。

这个问题源于我以前的问题同时使用MIT的开放课件学习Python / CS。 - 在这里看到我以前的问题 -

我使用下面的代码来制作月付款和其他东西的清单。然而，在循环结束时，我需要给付已付款总额的总计。

原始代码

  balance = float（raw_input（未清余额：））
 interestRate = float（raw_input（Interest Rate （1，12 + 1）中的月份：
 
 minPayRate = float（raw_input（最低月度支付率：））
 interestPaid = round （interestRate / 12.0 * balance，2）
 minPayment = round（minPayRate * balance，2）
 principalPaid = round（minPayment  -  interestPaid，2）
 remainingBalance = round（balance  -  principalPaid，2 ）
 
 
 print'月：％d'％（month，）
 print'最低每月付款：％.2f'％（minPayment，）
 print'付款原则：％.2f'％（principalPaid，）
 print'剩余余额：％.2f'％（remainingBalance，）
 
余额= remainingBalance 
 
 if月xrange（12，12 + 1）：
 print'RESULTS'
 print'支付的总额：'
 print'余额：％.2f'％（remainingBalance，）
  

问题是，我一直无法弄清楚如何保持付款总额。我尝试添加 totalPaid = round（interestPaid + principalPaid，2）但是这只是导致一个月的总和，我似乎无法得到它保持每个值月份，然后把它们全部加到最后打印出来。

另外我知道结果的金额应该是1131.12

我发现了很多这样做的例子，当每个值都知道，通过一个列表，但我似乎无法正确推断。

固定代码

 余额= float（raw_input（Outstanding Balance：））
 interestRate = float（raw_input（Interest Rate：））
 minPayRate = float（raw_input（Minimum Monthly Payment Rate：））$ b $ （1，12 + 1）中的月总计= 0 
 
：
 interestPaid = round（interestRate / 12.0 * balance，2）
 minPayment = round（minPayRate *余额，2）
 principalpaid = round（minPayment  -  interestPaid，2）
 remainingBalance = round（balance  -  principalPaid，2）
 totalPaid + = round（minPayment，2）
 
 print'月：％d'％（month，）
 print'最低每月付款：％.2f'％（minPayment，）
 print'付款原则：％.2f'％（principalPaid ，
 print'剩余余额：％.2f'％（remainingBalance，）
 $ b $余额= remainingBalance 
 
如果xrange（12，12 + 1） ：
打印'结果'
打印'支付的总金额：％。 2f'％（totalPaid，）
 print'余额：％.2f'％（remainingBalance，）
  

  total_paid =h2_lin>解决方案

= 0


然后，在循环体中添加适当的数量。您可以使用 + = 操作符添加到现有变量中，例如

  total_paid + = 1 
  

是 total_paid = total_paid + 1 。您不希望在每次迭代中给 total_paid 一个新的值，而是希望添加到它的现有值中。

<我不确定你的问题的具体情况，但是这是循环累积价值的一般形式。

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

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

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.

Original Code

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.

Also I know that the resulting amount should be 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.

Fixed Code

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,)

解决方案

Before your loop, initialize a variable to accumulate value:

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.

total_paid += 1

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

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

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