重新采样时间序列数据
频率转换和时间序列重采样的便捷方法。对象必须具有类似datetime的索引（DatetimeIndex， PeriodIndex或TimedeltaIndex），或将类似datetime的值传递给on或level关键字
DataFrame.resample(rule, axis=0, closed=None, label=None, convention='start', kind=None, loffset=None, base=None, on=None, level=None, origin='start_day', offset=None)[source]
参数：
rule：DateOffset, Timedelta or str，
axis：{0 or ‘index’, 1 or ‘columns’}, default 0，
closed：{‘right’, ‘left’}, default None
label：{‘right’, ‘left’}, default None
convention：{‘start’, ‘end’, ‘s’, ‘e’}, default ‘start’
kind：{‘timestamp’, ‘period’}, optional, default None
loffset：timedelta, default None
base：int, default 0
on：str, optional
level：str or int, optional
origin：{‘epoch’, ‘start’, ‘start_day’}, Timestamp or str, default ‘start_day’
offset：Timedelta or str, default is None