Question

这是一些数据的字典。当我打印它时，它打印在两个不同的列中。我在这里寻找了如何搜索它并找到特定数据的方法，但这对我没有任何意义。如果您能告诉我如何使用日期搜索此信息，然后打印出数据，那将不胜感激。

rainfall = {
    '01/08/2014':1.0,
    '21/01/2015':0.20,
    '22/01/2015':0.10,
    '23/01/2015':1.00,
    '24/01/2015':0.30,
    '25/01/2015':0.40,
    '26/01/2015':0.75,
    '27/01/2015':0.20,
    '28/01/2015':1.00,
    '29/01/2015':0.20,
    '30/01/2015':0.20,
    '31/01/2015':0.30,
    }

for k, v in rainfall.items():
    print(f'{k:<4} - {v}')


def searching_for_data():
    whatdata=input("What date would you like to find (format: DD/MM/YYYY)")
    if whatdata in rainfall:
        print(find(whatdata))


finddata=input("Would you like to find a specific piece of data?")
if finddata == "Yes":
    searching_for_data()

Answer 1

您需要更改：

if whatdata in rainfall:
    print(find(whatdata)

到

if whatdata in rainfall.keys():
    print(rainfall[whatdata])

Answer 2

您可以重写函数以利用dict.__getitem__或它的语法糖[]：

def searching_for_data():
    whatdata = input("What date would you like to find (format: DD/MM/YYYY)")
    if whatdata in rainfall:
        print(rainfall[whatdata])

但是您应该养成使用函数return值的习惯。如果您不希望看到None，那么如果密钥不存在，上述解决方案也将不起作用。例如，使用dict.get：

def searching_for_data():
    """Return value if it exists in dictionary, else None"""
    whatdata = input("What date would you like to find (format: DD/MM/YYYY)")
    return rainfall.get(whatdata)

finddata = input("Would you like to find a specific piece of data?")
if finddata == "Yes":
    data = searching_for_data()
    print(data)

Answer 3

您可以在searching_for_data中使用get函数：

def searching_for_data():
    whatdata = input("What date would you like to find (format: DD/MM/YYYY)")
    print(rainfall.get(whatdata, 'No data for ' + whatdata))

如果密钥不存在，它允许您定义默认值（或您的情况，提示用户）。

但是，更好的方法是让函数返回值并在顶层执行打印命令：

def searching_for_data():
    whatdata = input("What date would you like to find (format: DD/MM/YYYY)")
    return rainfall.get(whatdata, 'No data for ' + whatdata)

...

print(searching_for_data())

我希望能够使用日期查找特定的数据

3 个答案: