How do I add a column to an existing excel file using python?

Question

here is my code:

import openpyxl, pprint
wb = openpyxl.load_workbook('/Users/sarahporgess/Desktop/SSA1.xlsx')
sheet = wb.get_sheet_by_name('Sheet1')


data = {}
for row in range(1,sheet.max_row+1):


        date = sheet['A' +str(row)].value
        gamma = sheet['B' +str(row)].value
        theta = sheet['C' +str(row)].value
        ratio = float(gamma)/float(theta)
        resultFile = open('SSA2.csv' , 'w')
        resultFile.write( pprint.pformat(date))
        resultFile.write( pprint.pformat(gamma))
        resultFile.write( pprint.pformat(theta))

        resultFile.write( pprint.pformat(ratio))
        print(ratio)
        sheet['D1']=ratio
resultFile.close()
print('Done.')

my existing excel file currently has three columns: "date, gamma, theta". I want to add a fourth column called "ratio" that is the ratio of gamma/theta. How do I add another column to an existing excel document using python? This code creates an excel document with the 4 elements printed into one cell

Answer 1

It is easier to use the Pandas package

import pandas as pd
file_name = #Path to your file
df = pd.read_excel(file_name) #Read Excel file as a DataFrame

df['Ratio'] = df['Gamma']/df['Theta']
#Display top 5 rows to check if everything looks good
df.head(5)

#To save it back as Excel
df.to_excel("path to save") #Write DateFrame back as Excel file