Python共享单车项目输入报错求助：合法选项仍提示无效

Hey there, let's fix this issue right away! The problem is rooted in your get_filters() function—you've accidentally implemented two separate city-selection loops, and the second one is causing the confusion (plus it has an undefined variable bug).

What's Going Wrong #

1. Your first while loop works perfectly: it lets users pick a city via 1/2/3, assigns the correct city variable, and breaks out of the loop.
2. But immediately after that, another while loop starts asking users to type the city name (Chicago/New York/Washington). This is completely redundant, and worse—this loop references undefined variables like chicago (you defined uppercase constants CHICAGO, NYC, WASHINGTON instead).
3. When you input 1 for the first city selection, the program moves to this second loop. Since 1 isn't a valid city name, it triggers an error, making you think your first choice was invalid.

Fixed Code for get_filters() #

Here's the cleaned-up version of the function, removing the redundant city loop and fixing small inconsistencies:

def get_filters():
    """
    Asks user to specify a city, month, and day to analyze.
    Returns:
        (str) city - name of the city to analyze
        (int) month - number of the month to filter by, or None for no filter
        (int) day - index of the day of week to filter by, or None for no filter
    """
    invalid_choice = "Invalid choice..."
    ALL = 'all'
    print('Hello! Let\'s explore some US bikeshare data!')
    
    # Get user input for city (1=Chicago, 2=New York City, 3=Washington)
    while True:
        print("Please enter the number of which city you would like to explore: ")
        print("1 Chicago, 2 New York City, 3 Washington")
        location = input(">")
        if location == '1':
            city = CHICAGO
            print("You chose Chicago")
            break
        elif location == '2':
            city = NYC
            print("You chose New York City")
            break
        elif location == '3':
            city = WASHINGTON
            print("You chose Washington")
            break
        else:
            print(invalid_choice)
    
    # Get user input for month (1=January ... 6=June, or "all")
    while True:
        print(f"Please enter the number of the (start) month you would like to explore or \"{ALL}\": ")
        print("1 January ... 6 June")
        m = input(">")
        if m == ALL:
            month = None
            break
        try:
            month = int(m)
        except ValueError:
            print(invalid_choice)
            continue
        else:
            if 1 <= month <= 6:
                print(f"You chose {MONTHS_OF_YEAR[month-1]}")
                break
            elif month <= 12:
                print("Only January to June are in this dataset")
                print(invalid_choice)
                continue
            else:
                print(invalid_choice)
                continue
    
    # Get user input for day of week (1=Monday ...7=Sunday, or "all")
    while True:
        print(f"Please enter the number of the (start) day of the week that you would like to explore or \"{ALL}\": ")
        print("1 Monday ... 7 Sunday")
        d = input("> ")
        if d == ALL:
            day = None
            break
        try:
            day = int(d)
        except ValueError:
            print(invalid_choice)
            continue
        else:
            if 1 <= day <=7:
                day -= 1
                print(f"You chose {DAYS_OF_WEEK[day]}")
                break
            else:
                print(invalid_choice)
                continue
    
    print("-"*40)
    return city, month, day

Key Fixes Made #

• Removed the redundant second city-selection loop entirely
• Fixed the input prompt from > to > so users see a normal > character when entering input
• Used f-strings for cleaner string formatting (optional but improves readability)
• Added a clear divider (print("-"*40)) since your original code referenced print_divider() which wasn't defined (replace this with your actual divider function if you have one)

How to Test #

Run the modified code, input 1 when asked for the city—you'll see "You chose Chicago" and the program will proceed to the month selection step without any "Invalid choice..." errors.

内容的提问来源于stack exchange，提问作者Varun Wadhwa