How to group a Series by values in pandas?

Question

I currently have a pandas Series with dtype Timestamp, and I want to group it by date (and have many rows with different times in each group).

Answer 1

Three methods:

DataFrame: pd.groupby(['column']).size()

Series： sel.groupby(sel).size()

Series to DataFrame:

pd.DataFrame( sel, columns=['column']).groupby(['column']).size()