将 2D 列表分配给 2 个数据框列 Pandas

Question

我尝试了以下操作并出现错误：

>>> import pandas as pd

>>> df = pd.DataFrame([[0,0],[2,2]])

>>> df

   0  1

0  0  0

1  2  2

>>> y = [[0,0],[2,2],[3,3]]

>>> df["s","d"] = y

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

  File "C:\Python35\lib\site-packages\pandas\core\frame.py", line 3119, in __setitem__

    self._set_item(key, value)

  File "C:\Python35\lib\site-packages\pandas\core\frame.py", line 3194, in _set_item

    value = self._sanitize_column(key, value)

  File "C:\Python35\lib\site-packages\pandas\core\frame.py", line 3391, in _sanitize_column

    value = _sanitize_index(value, self.index, copy=False)

  File "C:\Python35\lib\site-packages\pandas\core\series.py", line 4001, in _sanitize_index

    raise ValueError('Length of values does not match length of ' 'index')

ValueError: Length of values does not match length of index

>>> df[["s","d"]] = y

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

  File "C:\Python35\lib\site-packages\pandas\core\frame.py", line 3116, in __setitem__

    self._setitem_array(key, value)

  File "C:\Python35\lib\site-packages\pandas\core\frame.py", line 3142, in _setitem_array

    indexer = self.loc._convert_to_indexer(key, axis=1)

  File "C:\Python35\lib\site-packages\pandas\core\indexing.py", line 1327, in _convert_to_indexer

    .format(mask=objarr[mask]))

KeyError: "['s' 'd'] not in index"

让我知道如何同时使用二维数组创建 2 列。

Answer 1

您无法在尝试时直接执行此操作，但这是一种解决方法：import pandas as pddf = pd.DataFrame([[0,0],[2,2]])y = [[0,0],[2,2]]df["s"], df["d"] = [i[0] for i in y], [i[1] for i in y]你有一些问题，其中之一df['s', 'd']是不正确的索引，你需要df[['s', 'd']]- 但你也不能直接从列表分配给它。你也不能分配比索引长的任何东西，所以你y = [[0,0],[2,2],[3,3]]太长了。