如何使用不同于输入& amp;的哨兵值按功能排序列表? [英] How to use sentinel values different from input & sort list by feature?

问题描述

我正在学习初学者python，我遇到了一个问题.

I'm learning beginner python and there's one question that I'm stuck on.

问题涉及询问用户输入的蘑菇量，输入重量，然后根据用户输入对蘑菇进行分类.为此，需要一个列表和while循环，以将输入追加到列表中.

The question involves asking user input for any amount of mushrooms that they have picked, entering a weight, and then sorting them according to the user input. For this, a list and a while loop is needed to append the inputs into the list.

当前，我正在尝试实现一个哨兵值，该值将在输入所有用户输入后停止while循环，但是将哨兵设置为"STOP"会与int()通知冲突.

Currently I am trying to implement a sentinel value that will stop the while loop after all of the user inputs have been entered, but setting the sentinel as "STOP" conflicts with the int() notification.

if __name__ == "__main__":
    STOP = "stop"
    mushroom = int(input("Enter a mushroom weight in grams, or STOP to end. "))
    total_list = []
    while total_list != STOP:
        total_list.append(mushroom)
        mushroom = int(input("Enter a mushroom weight in grams, or STOP to end. "))
    print(total_list)

程序运行良好，直到输入"STOP"(出现语法错误)为止.

The program runs well until entering "STOP", where a syntax error appears.

mushroom = int(input("Enter a mushroom weight in grams, or STOP to end. "))
ValueError: invalid literal for int() with base 10: 'STOP'

如您所见，前哨值STOP与我的输入建议冲突，从而导致错误.

As you can see, the sentinel value STOP conflicts with my input suggestion, resulting in an error.

对于问题的第二部分，我需要按权重对输入的值进行排序.如果一切都正确完成，我应该列出所有值. 我可以使用哪种代码对值进行排序? 我需要根据小(<100)，中(100-1000)和大(> 1000)对每个整数值进行排序，然后将结果打印在语句中. 我在这里需要做什么有点不知所措.

As for the second part of the problem, I need to sort the value inputs by weight. If everything has been done correctly, I should have a list with all the values. What kind of code can I use in order to sort the values? I need to sort each integer value based on small (<100), medium (100-1000), and large (>1000), then print the results in a statement. Am a little clueless regarding what I need to do here.

谢谢，只是停留在一个地方.

Thank you, just kind of stuck in one place.

推荐答案

您可以使用通过尝试使用Python中的try和except将非整数转换为整数而产生的错误.这是文档.

You can use the error produced by trying to convert a noninteger to an integer to your advantage with try and except in Python. Here is the documentation for that.

重写代码，您可以尝试以下操作:

Rewriting your code, you might try this:

if __name__ == "__main__":
    STOP = "STOP"
    total_list = []
    while True:
        try:
            user_input = input("Enter a mushroom weight in grams, or STOP to end. ")
            total_list.append(int(user_input))  
        except ValueError:
            if user_input.strip().upper()==STOP:
                break
            else:
                print("Incorrect entry! '{}' is not an integer".format(user_input))     

然后，如果您想对该列表进行排序并分类，则可以考虑使用字典:

Then if you want to sort that list and put into categories, you might consider using a dictionary:

total_list.sort()       
di={'Small':[],'Medium':[],'Large':[]}
for e in total_list:
    key='Small' if e<100 else 'Medium' if 100<=e<=1000 else 'Large'
    di[key].append(e)

print(total_list, sum(total_list),di)

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