groupby and aggregate pandas code example

Example 1: two groupby pandas

In [8]: grouped = df.groupby('A')

In [9]: grouped = df.groupby(['A', 'B'])

Example 2: pandas sum group by

df.groupby(['Fiscal_Year','Billing_Group'])['CHARGE_AMT'].sum()

Example 3: how can i aggregate without group by in pandas

df.groupby(lambda _ : True).agg(new_col_name = ('col_name', 'agg_function'))