pandas基础属性方法随机整理（五）---时间序列 resample方法

重采样及频率转换：
resample方法： 各种频率转换工作的主力函数

data.iloc[:,0:5].head()
Out[218]: 
              RPT    VAL    ROS    KIL    SHA
DATE                                         
1961-01-01  15.04  14.96  13.17   9.29    NaN
1961-01-02  14.71    NaN  10.83   6.50  12.62
1961-01-03  18.50  16.88  12.33  10.13  11.17
1961-01-04  10.58   6.63  11.75   4.58   4.54
1961-01-05  13.33  13.25  11.42   6.17  10.71

data.resample(‘M’, closed=’left’).mean().iloc[:,0:5].head()
注：use ” .resample(…).mean() ” 。.resample(.., how=’mean’)不推荐继续使用

data.resample('M', how='mean', closed='right').iloc[:,0:5].head()
*__main__:1: FutureWarning: how in .resample() is deprecated
the new syntax is .resample(...).mean()*
Out[215]: 
                  RPT        VAL        ROS       KIL        SHA
DATE                                                            
1961-01-31  14.518276  11.727586  13.322333  7.596000  10.953214
1961-02-28  16.672500  15.218214  14.522500  9.343333  13.791071
1961-03-31  11.022000  11.448387  10.807000  7.298000  10.682903
1961-04-30  10.632333   9.329000   9.984333  5.929333   8.479333
1961-05-31  10.011613   8.890333  10.730645  5.929000   9.528065

如下：常用参数，其中kind=period: 聚合到使其或时间戳，默认聚合到时间序列的索引类型。该例中时间序列的resample为’M’类型，因此kind参数聚合时间序列到‘Month’

data.resample('M', axis=0, closed='right',label='right', kind='period').mean().iloc[:,0:5].head()
Out[222]: 
               RPT        VAL        ROS       KIL        SHA
DATE                                                         
1961-01  14.841333  11.988333  13.431613  7.736774  11.072759
1961-02  16.269286  14.975357  14.441481  9.230741  13.852143
1961-03  10.890000  11.296452  10.752903  7.284000  10.509355
1961-04  10.722667   9.427667   9.998000  5.830667   8.435000
1961-05   9.860968   8.850000  10.818065  5.905333   9.490323

---

help()代码信息：

resample(self, rule, how=None, axis=0, fill_method=None, closed=None, label=None, convention='start', kind=None, loffset=None, limit=None, base=0, on=None, level=None)
    Convenience method for frequency conversion and resampling of time
    series.  Object must have a datetime-like index (DatetimeIndex,
    PeriodIndex, or TimedeltaIndex), or pass datetime-like values
    to the on or level keyword.

    Parameters
    ----------
    rule : string
        the offset string or object representing target conversion
    axis : int, optional, default 0
    closed : {'right', 'left'}
        Which side of bin interval is closed. The default is 'left'
        for all frequency offsets except for 'M', 'A', 'Q', 'BM',
        'BA', 'BQ', and 'W' which all have a default of 'right'.
    label : {'right', 'left'}
        Which bin edge label to label bucket with. The default is 'left'
        for all frequency offsets except for 'M', 'A', 'Q', 'BM',
        'BA', 'BQ', and 'W' which all have a default of 'right'.
    convention : {'start', 'end', 's', 'e'}
        For PeriodIndex only, controls whether to use the start or end of
        `rule`
    loffset : timedelta
        Adjust the resampled time labels
    base : int, default 0
        For frequencies that evenly subdivide 1 day, the "origin" of the
        aggregated intervals. For example, for '5min' frequency, base could
        range from 0 through 4. Defaults to 0
    on : string, optional
        For a DataFrame, column to use instead of index for resampling.
        Column must be datetime-like.

        .. versionadded:: 0.19.0

    level : string or int, optional
        For a MultiIndex, level (name or number) to use for
        resampling.  Level must be datetime-like.

        .. versionadded:: 0.19.0