如何开始在特定日期 pandas 时间组 [英] how to start time group on a specific date pandas

问题描述

我有一个按日期时间"12M"分组的df.我希望将其按12月31日结束的12M分组.目前是每年的1月31日结束的分组.似乎必须有一种简单的方法来进行此操作，但我一直找不到能找到我所要求的文件.我尝试设置TimeGrouper('12M')，但它不会从年初开始计数，而是使用第一个日期索引作为起点

I have a df that I have grouped by datetime '12M'. I would like it to be grouped by 12M ending Dec. 31. Currently it is yearly grouping ending Jan. 31. It seems that there must be a simple way of doing this but I have been unable to find anything documenting one I am asking for. I've tried setting TimeGrouper('12M') but it won't start the counting from the beginning of the year, but rather is uses the first date index as a starting point

dfy = dfy.groupby([pd.TimeGrouper('12M'), 'fec_id', 'trans_typ', 'cmte_id'])['amount'].sum()
dfy.head()
#dfy.to_csv('out.csv')

date        fec_id     trans_typ  cmte_id  
2007-01-31  C00002600  24K        C00000729    1000
                                  C00002840    1000
                                  C00004325    1000
                                  C00005157    1000
                                  C00009985    1000
Name: amount, dtype: int64

推荐答案

您可以使用 Grouper 与freq=A:

偏移别名.

g = df.groupby([pd.Grouper(level='date', freq='A'), 'cand_id', 'trans_typ'])['amount'].sum()
print g

date        cand_id    trans_typ
2001-12-31  H2HI02110  24K              2500
2007-12-31  H8IL21021  24K             -1000
            S6TN00216  24K              2000
2008-12-31  H2PA11098  24K              1000
            H4KS03105  24K             49664
            H6KS01146  24K              2000
            H6KS03183  24K              1000
            H8KS02090  24K              1000
            S6TN00216  24K              2500
2009-12-31  H0MO00019  24K               500
            H8MO09153  24K               500
            S0MO00183  24K              1000
            S0NY00410  24K                 0
            S2KY00012  24K              2000
            S6OH00163  24K             -4000
            S6TN00216  24K             -2000
            S6WY00068  24K             -3500   

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