Python惯例新手，我的代码方向对吗？

Question

我已经学习Python一周了，想试着做一个税率计算器。虽然还没完成，但我想知道我在Python编程方面是否走在正确的道路上。我之前只做过一点C++编程，感觉这对我现在的学习有影响（好还是不好呢？）

#There are six brackets define by the IRS as of 2009
#Schedule X - Single
first_bracket = 8350
second_bracket = 33950
third_bracket = 82250
fourth_bracket = 171550
fifth_bracket = 372950

def b1(a):
    a = a * .10
    return a
def b2(a):
    a = a * .15
    return a
def b3(a):
    a = a * .25
    return a
def b4(a):
    a = a * .28
    return a
def b5(a):
    a = a * .33
    return a
def b6(a):
    a = a * .35
    return a

if __name__ == '__main__': #importing is fun

    #Ask for salary
    salary = float(raw_input("Enter your salary\n"))    

    #First bracket
    if salary >= 0 and salary <= first_bracket:
        taxed = b1(salary)
        #print "You make less than $", float(first_bracket), "so your tax is $", taxed
        print taxed

    #Second bracket
    elif salary > first_bracket and salary <= second_bracket:
        taxed = b1(first_bracket) + b2(salary-first_bracket)
        #print "You make between $", first_bracket+1, "and $", second_bracket, "so your tax is $", taxed
        print taxed

    #Thrid bracket  
    elif salary > second_bracket and salary <= third_bracket:
        taxed = b1(first_bracket) + b2(second_bracket-first_bracket) + b3(salary-second_bracket)
        print taxed

Answer 1

使用4个空格来缩进代码！你可以看看这个文档，还有

import this

的输出，里面有更多信息。对我来说，这样的格式看起来不错，读起来也很简单。

Answer 2

特别是在处理财务数据时，你应该考虑使用 decimal 模块，这样可以确保你的结果没有浮点数错误。

如果你只是做一个小玩意儿来学习语言，这个问题不大，但了解这些对将来是有帮助的 :)

Answer 3

其实，有更简单的方法来处理这些数据，使用列表和配对，而不是为每个税率和限额单独设置变量。比如，看看下面的例子：

# List of (upper-limit, rate) pairs for brackets.
brackets = [ (8350, .10), (33950, .15), (82250, .25), (171550, .28), (372950, .33) ]

if __name__ == '__main__':

    salary = float(raw_input("Enter your salary\n"))

    accounted_for = 0 # Running total of the portion of salary already taxed
    taxed = 0 # Running total of tax from portion of salary already examined

    for (limit, rate) in brackets:
        if salary < limit:
            taxed += ( (salary - accounted_for) * rate )
            accounted_for = salary
            break # We've found the highest tax bracket we need to bother with
        else:
            taxed += ( (limit - accounted_for) * rate )
            accounted_for = limit

    # If we went over the max defined tax bracket, use the final rate
    if accounted_for < salary:
        taxed += ( (salary - accounted_for) * 0.35 )

    print taxed

这里的想法是，我们不想因为有多个类似的数据项就重复写代码。所有的税率区间的工作方式都是一样的，只是税率和限额不同而已。所以我们希望把这些不同的税率和限额当作输入，放到一个标准的计算中，而不是为每个区间写一个单独的函数。