Python：使用索引而不是嵌套循环进行2列输出的For循环

Question

我希望我的程序看起来像这样，但是当我运行程序时出现错误。我不知道我做错了什么请帮助我。太感谢了。对不起，我的英语不好

降雨统计

Month           Total Rainfall
-----           ---------------
Jan                  10
Feb                  20
Mar                  15
Apr                  5
May                  4
Jun                  5
Jul                  3
Aug                  2
Sep                  8
Oct                  7
Nov                  10
Dec                  12

Total Rainfall:      96
Average Rainfall:    8.0

这是我的代码：

amount = []
total = 0

month = ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec']
for num in range(1,13):
    am = int(raw_input("Enter amount of rainfall each month from Jan to Dec sequently: "))
    amount.append(am)
    total+=am

print "\nRainfall Statistics"
print "Month\t\tTotal Rainfall"
print "-----\t\t---------------"

for index in month:
    print month[index], "\t\t", amount[index]

print "\ntotal rainfall: ", total

average = total/12
print "\nAverage rainfall: ",average

这是我的输出：

Enter amount of rainfall each month from Jan to Dec sequently: 1
Enter amount of rainfall each month from Jan to Dec sequently: 2
Enter amount of rainfall each month from Jan to Dec sequently: 3
Enter amount of rainfall each month from Jan to Dec sequently: 4
Enter amount of rainfall each month from Jan to Dec sequently: 5
Enter amount of rainfall each month from Jan to Dec sequently: 6
Enter amount of rainfall each month from Jan to Dec sequently: 7
Enter amount of rainfall each month from Jan to Dec sequently: 8
Enter amount of rainfall each month from Jan to Dec sequently: 9
Enter amount of rainfall each month from Jan to Dec sequently: 10
Enter amount of rainfall each month from Jan to Dec sequently: 11
Enter amount of rainfall each month from Jan to Dec sequently: 12

Rainfall Statistics
Month       Total Rainfall
-----       ---------------

错误：

Traceback (most recent call last):
  File "/Users/matter_neverdie/Desktop/python/rainFall.py", line 15, in <module>
    print month[index], "\t\t", amount[index]
TypeError: list indices must be integers, not str

Answer 1

与 JavaScript 等其他语言不同，Python 使用 forin 循环遍历数组元素，而不是数组元素的索引。你的意思是

for index in range(len(month)):

Answer 2

你的程序应该和这个类似

from itertools import izip

amount = []
total = 0

month = ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec']
idx = 0
while(idx < len(month)):
    am = int(raw_input("Enter amount of rainfall each month from Jan to Dec sequently: "))
    amount.append(am)
    total+=am
    idx+=1

print "\nRainfall Statistics"
print "Month\t\tTotal Rainfall"
print "-----\t\t---------------"

for each_month, month_amount in izip(month, amount):
    print each_month, "\t\t", month_amount

print "\nTotal rainfall: ", total

average = total/12
print "\nAverage rainfall: ",average

当您在 Python 中使用 for 循环遍历列表时，您会得到元素，而不是像 C 风格的 for 循环那样的数字。

虽然迭代多个列表，但最好使用 itertools 模块中的工具，例如 izip，它有很多优点，而不是迭代一个列表并使用数字索引来迭代另一个列表。

您还应该了解何时需要在 Python 中使用 for 循环和 while 循环。尽管它们在 C 等语言中可能具有相同的目的，但它们可用于在 Python 中完成不同的事情。这个link 可能会帮助您了解何时使用 for 循环以及何时使用 while 循环。

Answer 3

首先，在你的输入循环中，写起来会更好 for num in range(12) 将循环 12 个 tiems 并为您提供索引 0..11。这比您的解决方案更受青睐，因为您不必考虑您真正拥有的 hov mny 迭代。

您可以对第二个循环使用完全相同的想法：

for index in range(12):

会起作用，但您可以通过使用len() 计算列表的长度（也许您希望两年后等）来改进这一点。所以你应该写

for index in range( len(month) ): #or len(amount)

在python中，您还可以使用内置的enumerate在一行中获取列表的索引和元素。 有了这个，您可以执行以下操作：

for index, month in enumerate(month):
    print month, "\t\t", amount[index]

最后一个例子可能不是你在作业中被要求做的；o)...