如何使用python解析包含毫秒的时间字符串？

Question

我能够用time.strTime分析包含日期/时间的字符串

>>> import time
>>> time.strptime('30/03/09 16:31:32', '%d/%m/%y %H:%M:%S')
(2009, 3, 30, 16, 31, 32, 0, 89, -1)

如何解析包含毫秒的时间字符串？

>>> time.strptime('30/03/09 16:31:32.123', '%d/%m/%y %H:%M:%S')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.5/_strptime.py", line 333, in strptime
    data_string[found.end():])
ValueError: unconverted data remains: .123

Answer 1

我知道这是一个老问题，但我仍在使用Python2.4.3，我需要找到一种更好的方法将数据字符串转换为日期时间。

如果datetime不支持%f且不需要尝试/排除，则解决方案是：

    (dt, mSecs) = row[5].strip().split(".") 
    dt = datetime.datetime(*time.strptime(dt, "%Y-%m-%d %H:%M:%S")[0:6])
    mSeconds = datetime.timedelta(microseconds = int(mSecs))
    fullDateTime = dt + mSeconds 

这适用于输入字符串“2010-10-06 09:42:52.266000”

Answer 2

Python 2.6添加了一个新的strftime/strptime宏%f，它执行微秒。不确定这是否有任何记录。但如果您使用的是2.6或3.0，则可以执行以下操作：

time.strptime('30/03/09 16:31:32.123', '%d/%m/%y %H:%M:%S.%f')

编辑：我从来没有真正使用过time模块，所以我一开始没有注意到这一点，但是time.struct_time似乎并不实际存储毫秒/微秒。您最好使用datetime，如下所示：

>>> from datetime import datetime
>>> a = datetime.strptime('30/03/09 16:31:32.123', '%d/%m/%y %H:%M:%S.%f')
>>> a.microsecond
123000

Answer 3

要给出nstehr's answer引用的代码（来自its source）：

def timeparse(t, format):
    """Parse a time string that might contain fractions of a second.

    Fractional seconds are supported using a fragile, miserable hack.
    Given a time string like '02:03:04.234234' and a format string of
    '%H:%M:%S', time.strptime() will raise a ValueError with this
    message: 'unconverted data remains: .234234'.  If %S is in the
    format string and the ValueError matches as above, a datetime
    object will be created from the part that matches and the
    microseconds in the time string.
    """
    try:
        return datetime.datetime(*time.strptime(t, format)[0:6]).time()
    except ValueError, msg:
        if "%S" in format:
            msg = str(msg)
            mat = re.match(r"unconverted data remains:"
                           " \.([0-9]{1,6})$", msg)
            if mat is not None:
                # fractional seconds are present - this is the style
                # used by datetime's isoformat() method
                frac = "." + mat.group(1)
                t = t[:-len(frac)]
                t = datetime.datetime(*time.strptime(t, format)[0:6])
                microsecond = int(float(frac)*1e6)
                return t.replace(microsecond=microsecond)
            else:
                mat = re.match(r"unconverted data remains:"
                               " \,([0-9]{3,3})$", msg)
                if mat is not None:
                    # fractional seconds are present - this is the style
                    # used by the logging module
                    frac = "." + mat.group(1)
                    t = t[:-len(frac)]
                    t = datetime.datetime(*time.strptime(t, format)[0:6])
                    microsecond = int(float(frac)*1e6)
                    return t.replace(microsecond=microsecond)

        raise