Examples
import numpy as np import pandas as pd
x = pd.Series([2, 1, 2, np.nan], index=['p', 'q', 'r', 's']) x
p 2.0 q 1.0 r 2.0 s NaN dtype: float64
y = pd.Series([1, np.nan, 2, 1], index=['p', 'q', 's', 't']) y
p 1.0 q NaN s 2.0 t 1.0 dtype: float64
x.subtract(y, fill_value=0)
p 1.0 q 1.0 r 2.0 s -2.0 t -1.0 dtype: float64