Pandas dataframe filter rows in condition but keep empty cells

Question

I am trying to filter out some rows by a condition value:

_a = my_df[my_df['A'] < 0.01]

But it also filters out rows with empty values. What I want is to filter rows that satisfy that condition and also keep empty values.

I am trying this but returns 0 rows. What I am doing wrong?

_a = my_df[pd.isnull(my_df['A']) | my_df['A'] < 0.01]

Thank you in advance!

jezrael · Accepted Answer · 2020-04-24 07:50:25Z

2

There are missing parentheses for second condition, because priority of operators:

_a = my_df[pd.isnull(my_df['A']) | (my_df['A'] < 0.01)]

_a = my_df[pd.isnull(my_df['A']) | my_df['A'].lt(0.01)]

answered Apr 24, 2020 at 7:50

jezrael

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2 Comments

oh my... thank you! How is this possible? Pandas is unable to interpret the operands of the conditions without parentheses?

@P.Solar - If chain condition then not.