如何压缩我的代码？ （格式和计算

Question

抱歉，我是编码新手，所以如果这是一个业余问题，我深表歉意。 一个练习要求我创建代码来计算 1,2 和 3 年投资的 4% 利息。 我已经复制了很多代码，并且想知道如何以不同的方式进行操作：以更简洁的方式。

例如，是否有可能将每年都转换成这样的float(year1, year2, year3)以适应多行代码？

startingBalance = input("Please enter your starting bank balance: ")
startingBalance = int(startingBalance)

year1 = (startingBalance * 1.04)
year2 = (year1 * 1.04)
year3 = (year2 * 1.04)
year1 = "{0:.2f}".format(year1)
year2 = "{0:.2f}".format(year2)
year3 = "{0:.2f}".format(year3)


print("Starting Balance: " + str(startingBalance) + "\n" + "Year 1 Balance: " + year1 + "\n" + "Year 2 Balance: " + year2 + "\n" + "Year 3 Balance: " + year3)

answer=str(input("would you like to withdraw your profits? Y/N: "))
if answer in ['Y', 'y']:
  startingBalance = float(startingBalance)
  year1 = float(year1)
  year2 = float(year2)
  year3 = float(year3)
  year1Profit = year1 - startingBalance
  year1Profit = "{0:.2f}".format(year1Profit)
  year2Profit = year2 - startingBalance
  year2Profit = "{0:.2f}".format(year2Profit)
  year3Profit = year3 - startingBalance
  year3Profit = "{0:.2f}".format(year3Profit)
  str(year3Profit)
  print("Year   | Balance | Profit " + "\n" + "Year 1  " + str(year1) + "       " + year1Profit  + "\n" + "Year 2  " + str(year2) + "       " + year2Profit  + "\n" + "Year 3  " + str(year3) + "       " + year3Profit)
elif answer in ['N', 'n']:
  print("Goodbye")
else:
  print("Invalid Entry")

Answer 1

从技术上讲，这是一行：

year1, year2, year3 = float(year1), float(year2), float(year3)

但是我认为如果您在初始化后不更改变量的类型会更清楚。 您可以始终将它们保留为浮点数，将打印行更改为：

print("Starting Balance: " + str(startingBalance) + "\n" + "Year 1 Balance: " + "{0:.2f}".format(year1) + "\n" + "Year 2 Balance: " + "{0:.2f}".format(year2) + "\n" + "Year 3 Balance: " + "{0:.2f}".format(year3))

这使您免于转换为字符串并再次转换回来。

Answer 2

这个问题在Code Review中可能更合适，但是：

year1 = "{0:.2f}".format(year1)

可以替换为：

year1 = round(year1, 2)

在我推荐使用一种类型的相同代码中使用 .format 和 print("foo" + bar)：

如果是 Python3.6 或更高版本，则为 F 字符串

print(f"Starting Balance: {startingBalance}\nYear 1 Balance: {year1}\nYear 2 Balance: {year2}\nYear 3 Balance: {year3}")

.format 如果 Python2 或 3 < 3.6

print("Starting Balance: {}\nYear 1 Balance: {}\nYear 2 Balance: {}\nYear 3 Balance: {}".format(startingBalance, year1, year2, year3))

无需将 str() 放在这里：

answer=str(input("would you like to withdraw your profits? Y/N: "))

input() 总是返回一个字符串。

当你想要（我猜）列表而不是一堆空格（丑陋）时使用“\ t”：

print("Year   | Balance | Profit " + "\n" + "Year 1  " + str(year1) + "       " + year1Profit  + "\n" + "Year 2  " + str(year2) + "       " + year2Profit  + "\n" + "Year 3  " + str(year3) + "       " + year3Profit)

同样的事情在这里使用 f-strings 或 .format 来格式化你的字符串。

Answer 3

为避免编写相同的代码，您可以创建 function 来计算最终余额和利润。 然后您可以使用其他答案来了解如何格式化变量并返回它们

def compute_year(starting_balance, number_of_year):
    return (startingBalance * 1.04 ** number_of_year, startingBalance * 1.04 ** number_of_year - startingBalance)

year1, year1Profit = compute_year(startingBalance, 1) 
year2, year2Profit = compute_year(startingBalance, 2) 
year3, year3Profit = compute_year(startingBalance, 3)

Answer 4

是的，很有可能，当你发现自己在写重复的代码行时，尝试使用函数！ 这样，您只需定义一次表达式！

例子：

year1 = (startingBalance * 1.04)
year2 = (year1 * 1.04)
year3 = (year2 * 1.04)

可以改成

def interest(balance):
    return balance * 1.04

year1 = interest(startingBalance)
year2 = interest(year1)

但这似乎仍然是重复的，对吧？ 现在尝试使用for循环：

current_balance = startingBalance
for year in range(4):
    current_balance = interest(current_balance)
    print(current_balance)

现在在每个循环中，您可以打印新余额的值，最后在 printg 行中添加一个漂亮的 output：您可以得到如下内容：

def interest(balance, years):
    return balance * (1.04 ** years)


def print_gains(balance, year):
    header = 'Year | Balance    | Profit   '
    print(header)
    print('-' * len(header))
    for year in range(1 + year):
        new_balance = interest(balance, year)
        print('%5d| %10.2f | %10.2f' % (year, new_balance, new_balance - balance))
    print()


def main():
    print_gains(10000, 5)

main()

产生以下 output：

Year | Balance    | Profit
-----------------------------
    0|   10000.00 |       0.00
    1|   10400.00 |     400.00
    2|   10816.00 |     816.00
    3|   11248.64 |    1248.64
    4|   11698.59 |    1698.59
    5|   12166.53 |    2166.53

我希望这可以帮助你！