What does this line do? df = df[~df[runner].str.contains("[a-z]").fillna(False)]

Question

may I check what does this line do?

df = df[~df[runner].str.contains("[a-z]").fillna(False)]

Is this code remove all rows that contain string that start with alphabet? 2nd question is what is the purpose of ~? What does it do?

Thanks

Possible duplicate of [Tilde sign in python dataframe](https://stackoverflow.com/questions/46054318/tilde-sign-in-python-dataframe) — Trenton McKinney, Oct 06 '19 at 00:12
Is it possible to add in a conditional to check if there are more than 3 chars as well in 1 line? — vitalstrike82, Oct 06 '19 at 03:40
The RegEx would be "[a-z]{3,}" which matches more than 3 characters from a to z. — tweini, Oct 06 '19 at 05:54

score 1 · Accepted Answer · answered Oct 06 '19 at 06:01

1

This code is masking a DataFrame.

The RegEx "[a-z]" means contains any character 'a to z' (not 'starting with', as this would be "^[a-z]").

The .fillna(False) means every NaN is treated as False for this Mask.

The ~ is inverting the Mask, so that the unselected rows are returned.

Be aware that the rows containing NaN are included. If this is not intended you must use .fillna(True).

answered Oct 06 '19 at 06:01

tweini

Worth noting possibly more idiomatic is to use the `na` parameter: `~df[runner].str.contains("[a-z]", na=False)` rather than using `fillna` as a subsequent step. – jpp Oct 07 '19 at 00:29

1 Answers1