How add new colum in existing excel using xlsx writer in python

I need to add a new column in my existing excel sheet which is .xlsx using Excel writer in python.

Name |sub1 |sub2 |sub3.
Ram. |10. |20. |30.
Raja.| 11. | 22. | 33

I need to added new columns for TOTAL and AVERAGE and need to calculate it and show the output in .xlsx file.

Need to do in Excel Writer

You can save the data into a xlsx file and use pandas to do the calculations like:

import pandas as pd 

df = pd.read_excel("test.xlsx")

total = df.sum(axis=1)  #sums all cells in row
average = df.mean(axis=1) #averages all cells in row

df.insert(loc = 4 , column = "Total", value = total )  #inserting sum to dataframe
df.insert(loc = 5 , column = "Average", value = average ) #inserting avg to dataframe

writer = pd.ExcelWriter("test.xlsx")
df.to_excel(writer,"Sheet1")    #Saving to df
writer.save()

You could also use df.to_excel("test.xlsx") to shorten the writing steps