python - 如何对使用 multiIndex 索引的 Dataframe 的 DataFrame 中的 DataFrame 执行操作

Question

我有一个包含许多其他数据框的数据框。这些都使用两个“级别”的索引进行索引。

现在我想对这些子数据帧进行一些操作（例如，取一行中所有值的平均值并将其添加到新行中）。由于我想迭代地执行此操作，因此我开始编写以下循环：

dfs_frame = pd.read_pickle(DATAFRAMESOUT + 'dfs_frame.pkl')
for name,video in dfs_frame.groupby(level=1):#returns tuple of (vid_name, dataframe)
    for frames in video[0]:
        print(frames)

这将返回一个帧列表。但是，一旦我尝试执行任何操作，例如，甚至只打印其中一列：

dfs_frame = pd.read_pickle(DATAFRAMESOUT + 'dfs_frame.pkl')
for name,video in dfs_frame.groupby(level=1):#returns tuple of (vid_name, dataframe)
    for frames in video[0]:
        print(frames['neutral'])

我收到以下错误：

    Traceback (most recent call last):
  File "C:\Users\chazzers\FER\venv\lib\site-packages\pandas\core\indexes\base.py", line 3361, in get_loc
    return self._engine.get_loc(casted_key)
  File "pandas\_libs\index.pyx", line 76, in pandas._libs.index.IndexEngine.get_loc
  File "pandas\_libs\index.pyx", line 108, in pandas._libs.index.IndexEngine.get_loc
  File "pandas\_libs\hashtable_class_helper.pxi", line 5198, in pandas._libs.hashtable.PyObjectHashTable.get_item
  File "pandas\_libs\hashtable_class_helper.pxi", line 5206, in pandas._libs.hashtable.PyObjectHashTable.get_item
KeyError: 'neutral'
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "D:\PyCharm 2020.1.4\plugins\python\helpers\pydev\_pydev_bundle\pydev_umd.py", line 197, in runfile
    pydev_imports.execfile(filename, global_vars, local_vars)  # execute the script
  File "D:\PyCharm 2020.1.4\plugins\python\helpers\pydev\_pydev_imps\_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "C:/Users/chazzers/FER/r-squared.py", line 145, in <module>
    print(frames['neutral'])
  File "C:\Users\chazzers\FER\venv\lib\site-packages\pandas\core\frame.py", line 3455, in __getitem__
    indexer = self.columns.get_loc(key)
  File "C:\Users\chazzers\FER\venv\lib\site-packages\pandas\core\indexes\base.py", line 3363, in get_loc
    raise KeyError(key) from err
KeyError: 'neutral'

非常感谢任何帮助。我希望这是足够的细节，可以让你理解我的问题。如果需要，很高兴澄清任何事情。

标签： pythonpandasdataframepandas-groupby