Pandas在列中列出列表？

Question

我正在尝试压缩一个列表列表：

    var         var2
0   9122532.0   [[458182615.0], [79834910.0]]
1   79834910.0  [[458182615.0], [9122532.0]]
2   458182615.0 [[79834910.0], [9122532.0]]

我想：

    var         var2
0   9122532.0   [458182615.0, 79834910.0]
1   79834910.0  [458182615.0, 9122532.0]
2   458182615.0 [79834910.0, 9122532.0]

应用

sample8['var2'] = sample8['var2'].apply(chain.from_iterable).apply(list)

给我：

    var1        var2
0   9122532.0   [[, 4, 5, 8, 1, 8, 2, 6, 1, 5, ., 0, ], [, 7, ...
1   79834910.0  [[, 4, 5, 8, 1, 8, 2, 6, 1, 5, ., 0, ], [, 9, ...
2   458182615.0 [[, 7, 9, 8, 3, 4, 9, 1, 0, ., 0, ], [, 9, 1, ...

Answer 1

数据：

In [162]: df
Out[162]:
           var                           var2
0    9122532.0  [[458182615.0], [79834910.0]]
1   79834910.0   [[458182615.0], [9122532.0]]
2  458182615.0    [[79834910.0], [9122532.0]]

解决方案：使用np.ravel()：

In [163]: df['var2'] = df['var2'].apply(np.ravel)

In [164]: df
Out[164]:
           var                       var2
0    9122532.0  [458182615.0, 79834910.0]
1   79834910.0   [458182615.0, 9122532.0]
2  458182615.0    [79834910.0, 9122532.0]

Answer 2

考虑数据框df

df = pd.DataFrame(dict(
        var=[9122532.0, 79834910.0, 458182615.0],
        var2=[[[458182615.0], [79834910.0]],
              [[458182615.0], [9122532.0]],
              [[79834910.0], [9122532.0]]]
    ))

print(df)

           var                           var2
0    9122532.0  [[458182615.0], [79834910.0]]
1   79834910.0   [[458182615.0], [9122532.0]]
2  458182615.0    [[79834910.0], [9122532.0]]

<强> np.concatenate
您可以apply np.concatenate

df.assign(var2=df.var2.apply(np.concatenate))

           var                       var2
0    9122532.0  [458182615.0, 79834910.0]
1   79834910.0   [458182615.0, 9122532.0]
2  458182615.0    [79834910.0, 9122532.0]

w / o apply
这要求所有都具有相同的2 x 1形状。它总是可以适应另一种形状。但是，这种方法仍然要求所有形状都是一致的。

df.assign(var2=np.array(df.var2.tolist()).reshape(-1, 2).tolist())

           var                       var2
0    9122532.0  [458182615.0, 79834910.0]
1   79834910.0   [458182615.0, 9122532.0]
2  458182615.0    [79834910.0, 9122532.0]

<强> 定时
小数据

大数据