Find index of all rows with null values in a particular column in pandas dataframe

Question

I have been worried about how to find indices of all rows with null values in a particular column of a pandas dataframe in python. If A is one of the entries in df.columns then I need to find indices of each row with null values in A

Answer 1

Supposing you need the indices as a list, one option would be:

df[df['A'].isnull()].index.tolist()

Answer 2

np.where(df['column_name'].isnull())[0]

np.where(Series_object) returns the indices of True occurrences in the column. So, you will be getting the indices where isnull() returned True.

The [0] is needed because np.where returns a tuple and you need to access the first element of the tuple to get the array of indices.

Similarly, if you want to get the indices of all non-null values in the column, you can run

np.where(df['column_name'].isnull() == False)[0]