cumulative sum in python code example

Example: cumulative sum in python

import pandas as pd
import numpy as np
  
# Create a dataframe
df1 = pd.DataFrame({"A":[None, 3, 8, 14], 
                   "B":[1, None, 4, 3], 
                   "C":[5, 3, 9,None]}) 
  
# Computing sum over Index axis
print(df1.cumsum(axis = 0, skipna = True))
#skipna exclude null values