rng = pd.date_range('1/1/2012', periods=100, freq='S')

返回：4s 数据
DatetimeIndex(['2012-01-01 00:00:00', '2012-01-01 00:00:01',
               '2012-01-01 00:00:02', '2012-01-01 00:00:03'],
              dtype='datetime64[ns]', freq='S')


ts = pd.Series(np.random.randint(0, 500, len(rng)), index=rng)

返回：
ts
2012-01-01 00:00:00    394
2012-01-01 00:00:01    186
2012-01-01 00:00:02    201
2012-01-01 00:00:03    389
Freq: S, dtype: int64


对2秒内的数据进行加和
ts.resample('2s').sum()