Excel Spreadsheet Manipulation with ord() and chr() in Python

import openpyxl, os
from openpyxl.styles import Font
from openpyxl.styles.colors import Color

'''
 Adapted from https://automatetheboringstuff.com/2e/chapter13/
 Data files used can be found at this link

 Formulas
 ========
 Excel formulas can configure cells to contain values calculated from other cells.

 >>> sheet['B9'] = '=SUM(B1:B8)'
 This will store =SUM(B1:B8) as the value in cell B9.

'''

os.chdir('/Google Drive/python_work/MyPythonScripts/datafiles')
print(os.getcwd())

wb = openpyxl.Workbook() # creates a WB with a single default sheet called 'Sheet'
wb.create_sheet(index=0, title='S1')
wb.create_sheet(index=1, title='S2')
wb.create_sheet(index=2, title='S3')
# Deleting default worksheet
try:
    del wb['Sheet']
    print('Removed Worksheet "Sheet"')
except KeyError:
    print('Worksheet "Sheet" does not exist')
print(wb.sheetnames)

myFont = Font(name='Arial', color='FF0000', size=14, bold=True)

# Set sheet 'S3' as active worksheet
wb.active = wb['S3']
print(wb.active)
# Manipulate sheet 'S3'
sheet = wb.active
sheet['A1'] = 200
sheet['A2'] = 300
# Set the formula.
sheet['A3'] = '=SUM(A1:A2)'
print(sheet['A3'].value)

# Set sheet 'S2' as active worksheet
wb.active = wb['S2']
print(wb.active)
sheet = wb.active
'''
# Set the Area's cell values using two for loops:
# The outer for goes over each row in the slice;
#   The nested for loop goes through each cell in that row,
#    sets the font to myFont
#    and sets the value to val
'''
for row in sheet['A1':'C4']:
    val = 0
    alpha = ord('A')
    chr(alpha)
    for cell in row:
        val += 1
        cell.value = val
        cell.font = myFont
'''
Sets the row segment (Area A5 to C5) to the sum of the cells in its column
ord('A') returns the ascii integer value for 'A' --> 65
chr(65) returns character value for ascii integer value 65 --> 'A'
Set alpha in the loop to increment by 1 and then use chr(alpha) to move from
column A to B to C. This loop accomplishes the same task as doing this:

 sheet['A5'] = '=SUM(A1:A4)'
 sheet['B5'] = '=SUM(B1:B4)'
 sheet['C5'] = '=SUM(C1:C4)'
'''
number = 5
i = 0
for row in sheet['A5':'C5']:
    for cell in row:
        alpha = ord('A') + i
        alphaNum = '%s%s' %(chr(alpha), number)
        print('%s   %s   %s' %(alphaNum, alpha, i))
        sheet[alphaNum] = '=SUM(%s1:%s4)' %(chr(alpha), chr(alpha))
        i += 1


wb.save('formulas.xlsx')
wb.close()