Openpyxl 1.8.5: Reading the result of a formula typed in a cell using openpyxl

openpyxl support either the formula or the value of the formula. You can select which using the data_only flag when opening a workbook. However, openpyxl does not and will not calculate the result of a formula. There are libraries out there like pycel which purport to do this.

xlwings, PyXll FlyingKoala, DataNitro all use Excel as the interface to using Python.

If you want to use a Python library you can try PyCel, xlcalculator, Formulas and Schedula.

I am the project owner of xlcalculator.

xlcalculator uses openpyxl to read Excel files and adds functionality which translates Excel formulas into Python.

An example using xlcalculator with an Excel file:

from xlcalculator import ModelCompiler
from xlcalculator import Model
from xlcalculator import Evaluator

filename = r'use_case_01.xlsm'
compiler = ModelCompiler()
new_model = compiler.read_and_parse_archive(filename)
evaluator = Evaluator(new_model)
val1 = evaluator.evaluate('First!A2')
print("value 'evaluated' for First!A2:", val1)

An example using xlcalculator with a dict;

input_dict = {
    "B4": 0.95,
    "B2": 1000,
    "B19": 0.001,
    "B20": 4,
    # B21
    "B22": 1,
    "B23": 2,
    "B24": 3,
    "B25": "=B2*B4",
    "B26": 5,
    "B27": 6,
    "B28": "=B19*B20*B22",
    "C22": "=SUM(B22:B28)",
  }

from xlcalculator import ModelCompiler
from xlcalculator import Model
from xlcalculator import Evaluator

compiler = ModelCompiler()
my_model = compiler.read_and_parse_dict(input_dict)
evaluator = Evaluator(my_model)

for formula in my_model.formulae:
    print("Formula", formula, "evaluates to", evaluator.evaluate(formula))

# cells need a sheet and Sheet1 is default.
evaluator.set_cell_value("Sheet1!B22", 100)
print("Formula B28 now evaluates to", evaluator.evaluate("Sheet1!B28"))
print("Formula C22 now evaluates to", evaluator.evaluate("Sheet1!C22"))

I have solved the matter using a combination of openpyxl and pandas:

import pandas as pd
import openpyxl
from openpyxl import Workbook , load_workbook


source_file = "Test.xlsx"
# write to file
wb = load_workbook (source_file)
ws = wb.active
ws.title = "hello world"
ws.append ([10,10])
wb.save(source_file)

# read from file
df = pd.read_excel(source_file)
sum_jan = df ["Jan"].sum() 
print (sum_jan)

Openpyxl doesn't support excel 100% for calculating the formula. It supports only very basic formulas. If you want to calculate all formula in workbook you should use xlwings library (which is supported on MacOS and Windows only).