utils.py 文件源码

def get_lookback(lookback_length):
    """Take a string from the user and return a datetime.timedelta object."""
    time_units = {'weeks': 0, 'days': 0, 'hours': 0} 
    time_shortunits = [x[0] for x in time_units.keys()]
    lookback_unit = lookback_length[-1]
    lookback_value = lookback_length[:-1]

    try:
        lookback_unit = next(i for i in list(time_units) if
                             i.startswith(lookback_unit))
    except StopIteration:
        panic("hs_history_lookback time unit {lookback_unit} is not "
            "suppported. Please choose one of: "
            "{time_shortunits}.".format(**locals()))
    try:
        time_units[lookback_unit] = int(lookback_value)
    except ValueError as exc:
        panic("hs_history_lookback should be an integer value followed by a "
              "single time unit element from {time_shortunits}.\n"
              "ValueError: {exc}".format(**locals()))

    lookback_timedelta = timedelta(weeks=time_units['weeks'],
                                   days=time_units['days'],
                                   hours=time_units['hours'])
    return lookback_timedelta