列出中的Pandas DataFrame列值

问题描述

我有一个熊猫 DataFrame 像这样

                          clusters
0                              [4]
1                  [9, 14, 16, 19]
2           [6, 7, 10, 17, 18, 20]
3  [1, 2, 3, 5, 8, 11, 12, 13, 15]

我只需要获取整数群集列。像下面这样（这可以是四个列表，不需要另一个 DataFrame ）

I need to get only the integer values in the cluster column separately. Like following(This can be four lists no need of having another DataFrame)

0                              4
1                  9, 14, 16, 19
2           6, 7, 10, 17, 18, 20
3  1, 2, 3, 5, 8, 11, 12, 13, 15

我尝试了不同的方法。无法达到预期的输出。

I tried different things. Could not achieve the expected output.

In [36]: clustlist = list(firstclusters.clusters.values)
Out[36]:
    [array([4]), array([ 9, 14, 16, 19]), array([ 6,  7, 10, 17, 18, 20]), array([ 1,  2,  3,  5,  8, 11, 12, 13, 15])]

In [37]: np.ravel(clustlist)
Out[37]:
    [array([4]) array([ 9, 14, 16, 19]) array([ 6,  7, 10, 17, 18, 20])
     array([ 1,  2,  3,  5,  8, 11, 12, 13, 15])]

In [38]: np.hstack(clustlist)
Out[38]:
    [ 4  9 14 16 19  6  7 10 17 18 20  1  2  3  5  8 11 12 13 15]

推荐答案

如果每个项目只是一个列表，则可以使用tolist系列方法：

If each item is just a list, you can use the tolist Series method:

In [11]: df.clusters.tolist()
Out[11]: [[4], [9, 14, 16, 19], [6, 7, 10, 17, 18, 20], [1, 2, 3, 5, 8, 11, 12, 13, 15]]

或者，如果这些是numpy数组，您需要首先对每个项目应用列表：

Or, if these are numpy arrays you need to apply tolist to each item first:

In [12]: df.clusters.apply(np.ndarray.tolist).tolist()
Out[12]: [[4], [9, 14, 16, 19], [6, 7, 10, 17, 18, 20], [1, 2, 3, 5, 8, 11, 12, 13, 15]]

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