Question

我正在编写一个函数来使用数据框中每行的信息来选择另一个数据帧中的一些观察结果并返回一个数据框或列表：

  df = pd.DataFrame({"D": [10,20,30], "p": [20, 30, 10]})

  df1 = pd.DataFrame({"W": [20,30,30], "G": [10, 40, 10]})

  def Compute(row):

      df1.State = df1.apply(lambda r: 1 if r.W > row['D'] else 0, axis = 1)

      df2 = df1[ (df1.State == 1) ]

      if len(df2) > 0:

           return df2

 df.apply(Compute, axis = 1)

但是，我总是收到这样的错误：

    Traceback (most recent call last):

    File "<ipython-input-96-c5fdc35977db>", line 1, in <module>
df.apply(Compute, axis = 1)

    File "C:\Users\Research\Anaconda3\lib\site-packages\pandas\core\frame.py", line 3972, in apply
    return self._apply_standard(f, axis, reduce=reduce)

    File "C:\Users\Research\Anaconda3\lib\site-packages\pandas\core\frame.py", line 4081, in _apply_standard
    result = self._constructor(data=results, index=index)

    File "C:\Users\Research\Anaconda3\lib\site-packages\pandas\core\frame.py", line 226, in __init__
    mgr = self._init_dict(data, index, columns, dtype=dtype)

    File "C:\Users\Research\Anaconda3\lib\site-packages\pandas\core\frame.py", line 363, in _init_dict
dtype=dtype)

    File "C:\Users\Research\Anaconda3\lib\site-packages\pandas\core\frame.py", line 5163, in _arrays_to_mgr
    arrays = _homogenize(arrays, index, dtype)

    File "C:\Users\Research\Anaconda3\lib\site-packages\pandas\core\frame.py", line 5477, in _homogenize
    raise_cast_failure=False)

    File "C:\Users\Research\Anaconda3\lib\site-packages\pandas\core\series.py", line 2887, in _sanitize_array
    subarr = _asarray_tuplesafe(data, dtype=dtype)

    File "C:\Users\Research\Anaconda3\lib\site-packages\pandas\core\common.py", line 2011, in _asarray_tuplesafe
    result[:] = [tuple(x) for x in values]

    ValueError: cannot copy sequence with size 2 to array axis with dimension 3

有没有办法完成这项工作？

函数可以在python中返回数据框或列表吗？

0 个答案: