python - 使用 Pandas Panel 在非唯一轴上分组

Question

我有一个带有非唯一 major_axis 的 pandas Panel，我正在尝试使用 groupby 对非唯一行求和，但我收到一条错误消息，指出 major_axis 不可迭代。我搜索了堆栈溢出和留言板，但似乎面板没有数据框那样广泛使用。

这是一个产生错误的例子:

import pandas as pd
import datetime as dt
import dateutil.relativedelta as rd
import numpy as np

items = ['A','B']
minor_axis = ['x','y']

diff = rd.relativedelta(years=1)

major_axis = [dt.date(2013,1,1) + (diff * shift) for shift in xrange(4)] * 2

values = np.random.randn(2,8,2)

data = pd.Panel(data=values, major_axis=major_axis, minor_axis=minor_axis, items=items)

data.groupby(sum, axis='major')

这是堆栈跟踪:

    ---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-29-e30fb9b32fce> in <module>()
----> 1 data.groupby(sum, axis='major')

/home/brendan/python_dev/venv/local/lib/python2.7/site-packages/pandas/core/panel.pyc in groupby(self, function, axis)
   1084         from pandas.core.groupby import PanelGroupBy
   1085         axis = self._get_axis_number(axis)
-> 1086         return PanelGroupBy(self, function, axis=axis)
   1087 
   1088     def swapaxes(self, axis1='major', axis2='minor', copy=True):

/home/brendan/python_dev/venv/local/lib/python2.7/site-packages/pandas/core/groupby.pyc in __init__(self, obj, keys, axis, level, grouper, exclusions, selection, as_index, sort, group_keys, squeeze)
    195         if grouper is None:
    196             grouper, exclusions = _get_grouper(obj, keys, axis=axis,
--> 197                                                level=level, sort=sort)
    198 
    199         self.grouper = grouper

/home/brendan/python_dev/venv/local/lib/python2.7/site-packages/pandas/core/groupby.pyc in _get_grouper(obj, key, axis, level, sort)
   1323             raise AssertionError(errmsg)
   1324 
-> 1325         ping = Grouping(group_axis, gpr, name=name, level=level, sort=sort)
   1326         groupings.append(ping)
   1327 

/home/brendan/python_dev/venv/local/lib/python2.7/site-packages/pandas/core/groupby.pyc in __init__(self, index, grouper, name, level, sort)
   1197             # no level passed
   1198             if not isinstance(self.grouper, np.ndarray):
-> 1199                 self.grouper = self.index.map(self.grouper)
   1200                 if not (hasattr(self.grouper,"__len__") and \
   1201                    len(self.grouper) == len(self.index)):

/home/brendan/python_dev/venv/local/lib/python2.7/site-packages/pandas/core/index.pyc in map(self, mapper)
    856 
    857     def map(self, mapper):
--> 858         return self._arrmap(self.values, mapper)
    859 
    860     def isin(self, values):

/home/brendan/python_dev/venv/local/lib/python2.7/site-packages/pandas/algos.so in pandas.algos.arrmap_object (pandas/algos.c:62269)()

TypeError: 'datetime.date' object is not iterable

关于如何处理这种情况有什么想法吗？

非常感谢，

布兰登

Answer 1

在0.12你可以试试

>>> data.groupby(np.sum, axis='major')
<pandas.core.groupby.PanelGroupBy object at 0x1a2ba50>