Examples
By default, the product of an empty or all-NA Series is 1:

In [1]:
import numpy as np
import pandas as pd
In [2]:
pd.Series([]).product()
Out[2]:
1.0

This can be controlled with the min_count parameter:

In [3]:
pd.Series([]).product(min_count=1)
Out[3]:
nan
In [4]:
pd.Series([np.nan]).product()
Out[4]:
1.0
In [5]:
pd.Series([np.nan]).product(min_count=1)
Out[5]:
nan