python从csv获取数据类型-日期时间和时间为"2305“

Question

如何从csv文件中获取日期时间和时间的数据类型：

        with open(dataPath, newline='') as csvData:
             reader = csv.DictReader(csvData, delimiter=';')
             head = next(reader)
             .
             .

我有以下csv文件：

        "...."; "YEAR"; "TIME"; "..." --> head
        "...."; "19.05.2020"; "0050"; "..." --> "0050" means 00:50
        "...."; "12.05.2020"; "2035"; "..." --> "2035" means 20:35

我用一个函数尝试了一下：

def convert(value):
    heuristics = [lambda value: datetime.strptime(value, "%d.%m.%Y"), datetime.strptime(value, "%H%D"), int, float]
    for type in heuristics:
        try:
            return type(value)
        except ValueError:
            continue
    # All other heuristics failed it is a string
    return value

如果我有一个值"1,2,3“，它会输出一个值error，但为此我写了除了ValueError: continue，为什么当这个错误发生时，它不继续，和"513165”一样

谢谢

Answer 1

如果你想让它正常工作，有几件事：

strptime operations

• %D不是有效的strptime指令，我假设您的意思是重新定义内置的type

• better

• 并打印错误，以了解

上发生了什么

使用一些测试的工作示例(但不要假设所有可能的错误都会被完全覆盖...)

def convert(value):
    heuristics = [lambda value: datetime.strptime(value, "%d.%m.%Y"),
                  lambda value: datetime.strptime(value, "%H%M"),
                  int,
                  float]
    for f in heuristics:
        try:
            return f(value)
        except ValueError as e:
            print(f"encountered error: {e}")
            continue
    # All other heuristics failed it is a string
    return value


for v in ('2355', 'asdf', '12', '3.14', '7.12.2013'):
    print(f"testing '{v}'...")
    result = convert(v)
    print(result, type(result))

给你

testing '2355'...
encountered error: time data '2355' does not match format '%d.%m.%Y'
1900-01-01 23:55:00 <class 'datetime.datetime'>
testing 'asdf'...
encountered error: time data 'asdf' does not match format '%d.%m.%Y'
encountered error: time data 'asdf' does not match format '%H%M'
encountered error: invalid literal for int() with base 10: 'asdf'
encountered error: could not convert string to float: 'asdf'
asdf <class 'str'>
testing '12'...
encountered error: time data '12' does not match format '%d.%m.%Y'
1900-01-01 01:02:00 <class 'datetime.datetime'>
testing '3.14'...
encountered error: time data '3.14' does not match format '%d.%m.%Y'
encountered error: time data '3.14' does not match format '%H%M'
encountered error: invalid literal for int() with base 10: '3.14'
3.14 <class 'float'>
testing '7.12.2013'...
2013-12-07 00:00:00 <class 'datetime.datetime'>