Reversal of string.contains In python, pandas

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]

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.