Python-如果两列均为NaN，则删除行 [英] Python - Drop row if two columns are NaN

问题描述

这是对

This is an extension to this question, where OP wanted to know how to drop rows where the values in a single column are NaN.

我想知道如何在 2 (或更多)列均为 NaN 的情况下删除行.使用第二个答案的创建的数据框:

I'm wondering how I can drop rows where the values in 2 (or more) columns are both NaN. Using the second answer's created Data Frame:

In [1]: df = pd.DataFrame(np.random.randn(10,3))

In [2]: df.ix[::2,0] = np.nan; df.ix[::4,1] = np.nan; df.ix[::3,2] = np.nan;

In [3]: df
Out[3]:
          0         1         2
0       NaN       NaN       NaN
1  2.677677 -1.466923 -0.750366
2       NaN  0.798002 -0.906038
3  0.672201  0.964789       NaN
4       NaN       NaN  0.050742
5 -1.250970  0.030561 -2.678622
6       NaN  1.036043       NaN
7  0.049896 -0.308003  0.823295
8       NaN       NaN  0.637482
9 -0.310130  0.078891       NaN

如果我使用drop.na()命令(特别是drop.na(subset=[1,2]))，则会完成一个或"类型的放置并离开:

If I use the drop.na() command, specifically the drop.na(subset=[1,2]), then it completes an "or" type drop and leaves:

In[4]: df.dropna(subset=[1,2])
Out[4]: 
          0         1         2
1  2.677677 -1.466923 -0.750366
2       NaN  0.798002 -0.906038
5 -1.250970  0.030561 -2.678622
7  0.049896 -0.308003  0.823295

我想要的是一个和"类型的放置，它将放置在列索引1 和 2中有NaN的行中.这会留下:

What I want is an "and" type drop, where it drops rows where there is an NaN in column index 1 and 2. This would leave:

          0         1         2
1  2.677677 -1.466923 -0.750366
2       NaN  0.798002 -0.906038
3  0.672201  0.964789       NaN
4       NaN       NaN  0.050742
5 -1.250970  0.030561 -2.678622
6       NaN  1.036043       NaN
7  0.049896 -0.308003  0.823295
8       NaN       NaN  0.637482
9 -0.310130  0.078891       NaN

仅放置第一行的地方.

有什么想法吗?

更改数据框的值以保持一致性

changed data frame values for consistency

推荐答案

以下两个之一:

df.dropna(subset=[1, 2], how='all')

或

df.dropna(subset=[1, 2], thresh=1)

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