Pandas DataFrame 选择具有 NaN 值的特定列

Pandas DataFrame select the specific columns with NaN values

提问by Fan

I have a two-column DataFrame, I want to select the rows with NaNin either column.

我有一个两列的 DataFrame，我想选择NaN任一列中的行。

I used this method df[ (df['a'] == np.NaN) | (df['b'] == np.NaN) ]
However it returns an empty answer. I don't know what's the problem

我使用了这个方法df[ (df['a'] == np.NaN) | (df['b'] == np.NaN) ]
但是它返回一个空答案。我不知道有什么问题

采纳答案by jezrael

You need isnullfor finding NaNvalues:

您需要isnull查找NaN值：

df[ (df['a'].isnull()) | (df['b'].isnull()) ]

Docs.

文档。

回答by piRSquared

You could apply isnull()to the whole dataframe then check if the rows have any nulls with any(1)

您可以应用isnull()到整个数据框然后检查行是否有任何空值any(1)

df[df.isnull().any(1)]

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Timing

定时

df = pd.DataFrame(np.random.choice((np.nan, 1), (1000000, 2), p=(.2, .8)), columns=['A', 'B'])

I did not expect these results...

没想到这个结果...