反转string.contains在python，pandas中 [英] Reversal of string.contains In python, pandas

问题描述

我的代码中有类似的内容:

I have something like this in my code:

df2 = df[df['A'].str.contains("Hello|World")]

但是，我希望所有不的行都包含Hello或World.如何最有效地扭转这种情况?

However, I want all the rows that don't contain either of Hello or World. How do I most efficiently reverse this?

推荐答案

您可以使用波浪号~来反转布尔值:

You can use the tilde ~ to flip the bool values:

>>> df = pd.DataFrame({"A": ["Hello", "this", "World", "apple"]})
>>> df.A.str.contains("Hello|World")
0     True
1    False
2     True
3    False
Name: A, dtype: bool
>>> ~df.A.str.contains("Hello|World")
0    False
1     True
2    False
3     True
Name: A, dtype: bool
>>> df[~df.A.str.contains("Hello|World")]
       A
1   this
3  apple

[2 rows x 1 columns]

这不是最有效的方法吗?您必须将其与其他选项相对应.有时使用正则表达式比df[~(df.A.str.contains("Hello") | (df.A.str.contains("World")))]之类的东西要慢，但是我很难猜测交叉点在哪里.

Whether this is the most efficient way, I don't know; you'd have to time it against your other options. Sometimes using a regular expression is slower than things like df[~(df.A.str.contains("Hello") | (df.A.str.contains("World")))], but I'm bad at guessing where the crossovers are.

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