metadata.py 文件源码

def voltages(fileobject, time_bins_size='1min', tz='US/Eastern'):
    """Creates a DataFrame of voltages, for each member and time bin.

    Parameters
    ----------
    fileobject : file or iterable list of str
        The proximity data, as an iterable of JSON strings.

    time_bins_size : str
        The size of the time bins used for resampling.  Defaults to '1min'.

    tz : str
        The time zone used for localization of dates.  Defaults to 'US/Eastern'.

    Returns
    -------
    pd.Series :
        Voltages, indexed by datetime and member.
    """

    def readfile(fileobject):
        for line in fileobject:
            data = json.loads(line)['data']

            yield (data['timestamp'],
                   str(data['member']),
                   float(data['voltage']))

    df = pd.DataFrame(readfile(fileobject), columns=['timestamp', 'member', 'voltage'])

    # Convert the timestamp to a datetime, localized in UTC
    df['datetime'] = pd.to_datetime(df['timestamp'], unit='s', utc=True) \
                       .dt.tz_localize('UTC').dt.tz_convert(tz)
    del df['timestamp']

    # Group by id and resample
    df = df.groupby([
        pd.TimeGrouper(time_bins_size, key='datetime'),
        'member'
    ]).mean()

    df.sort_index(inplace=True)

    return df['voltage']