How to create a pivot table in Excel with python win32com

Question

• Given an existing Excel file, with data in a long format

  • 

• Automate creating the following pivot table in Excel with the Python win32com module

  • 

• Following is code to setup test.xlsx with data and connect to create a Excel com object

Imports

import win32com.client as win32
from pathlib import Path
import sys
import pandas as pd
import numpy as np
import random
from datetime import datetime

win32c = win32.constants

Function to create test.xlsx

• This function is only to provide test data and a file

def create_test_excel_file(f_path: Path, f_name: str, sheet_name: str):
    
    filename = f_path / f_name
    random.seed(365)
    np.random.seed(365)
    number_of_data_rows = 1000
    
    # create list of 31 dates
    dates = pd.bdate_range(datetime(2020, 7, 1), freq='1d', periods=31).tolist()

    data = {'date': [random.choice(dates) for _ in range(number_of_data_rows)],
            'expense': [random.choice(['business', 'personal']) for _ in range(number_of_data_rows)],
            'products': [random.choice(['book', 'ribeye', 'coffee', 'salmon', 'alcohol', 'pie']) for _ in range(number_of_data_rows)],
            'price': np.random.normal(15, 5, size=(1, number_of_data_rows))[0]}

    pd.DataFrame(data).to_excel(filename, index=False, sheet_name=sheet_name, float_format='%.2f')

Function to create Excel com object

def run_excel(f_path: Path, f_name: str, sheet_name: str):

    filename = f_path / f_name

    # create excel object
    excel = win32.gencache.EnsureDispatch('Excel.Application')

    # excel can be visible or not
    excel.Visible = True  # False
    
    # try except for file / path
    try:
        wb = excel.Workbooks.Open(filename)
    except com_error as e:
        if e.excepinfo[5] == -2146827284:
            print(f'Failed to open spreadsheet.  Invalid filename or location: {filename}')
        else:
            raise e
        sys.exit(1)

    # set worksheet
    ws1 = wb.Sheets('data')
    
#     wb.Close(True)
#     excel.Quit()

Main

def main():
    # sheet name for data
    sheet_name = 'data'  # update with sheet name from your file
    # file path
    f_path = Path.cwd()  # file in current working directory
#   f_path = Path(r'c:\...\Documents')  # file located somewhere else
    # excel file
    f_name = 'test.xlsx'
    
    # function calls
    create_test_excel_file(f_path, f_name, sheet_name)  # remove when running your own file
    run_excel(f_path, f_name, sheet_name)

Answer 1

• A helpful way to figure out the proper Excel methods to use, is record a step-by-step Macro in Excel, while creating a pivot table in the form you want.
  • This is useful for creating a pivot table that has to be run on a routine basis in a file with existing data.
• Uses the imports and methods from the question
• To modify this code for a new data file
  • Update def main
    • sheet_name
    • f_path
    • f_name
  • Update def run_excel
    • ws1
    • ws2_name
    • pt_name
    • pt_rows
    • pt_cols
    • pt_filters
    • pt_fields
  • Call main() to run code

pivot_table function

def pivot_table(wb: object, ws1: object, pt_ws: object, ws_name: str, pt_name: str, pt_rows: list, pt_cols: list, pt_filters: list, pt_fields: list):
    """
    wb = workbook1 reference
    ws1 = worksheet1
    pt_ws = pivot table worksheet number
    ws_name = pivot table worksheet name
    pt_name = name given to pivot table
    pt_rows, pt_cols, pt_filters, pt_fields: values selected for filling the pivot tables
    """

    # pivot table location
    pt_loc = len(pt_filters) + 2
    
    # grab the pivot table source data
    pc = wb.PivotCaches().Create(SourceType=win32c.xlDatabase, SourceData=ws1.UsedRange)
    
    # create the pivot table object
    pc.CreatePivotTable(TableDestination=f'{ws_name}!R{pt_loc}C1', TableName=pt_name)

    # selecte the pivot table work sheet and location to create the pivot table
    pt_ws.Select()
    pt_ws.Cells(pt_loc, 1).Select()

    # Sets the rows, columns and filters of the pivot table

    for field_list, field_r in ((pt_filters, win32c.xlPageField), (pt_rows, win32c.xlRowField), (pt_cols, win32c.xlColumnField)):
        for i, value in enumerate(field_list):
            pt_ws.PivotTables(pt_name).PivotFields(value).Orientation = field_r
            pt_ws.PivotTables(pt_name).PivotFields(value).Position = i + 1

    # Sets the Values of the pivot table
    for field in pt_fields:
        pt_ws.PivotTables(pt_name).AddDataField(pt_ws.PivotTables(pt_name).PivotFields(field[0]), field[1], field[2]).NumberFormat = field[3]

    # Visiblity True or Valse
    pt_ws.PivotTables(pt_name).ShowValuesRow = True
    pt_ws.PivotTables(pt_name).ColumnGrand = True

Update run_excel to call pivot_table

def run_excel(f_path: Path, f_name: str, sheet_name: str):

    filename = f_path / f_name

    # create excel object
    excel = win32.gencache.EnsureDispatch('Excel.Application')

    # excel can be visible or not
    excel.Visible = True  # False
    
    # try except for file / path
    try:
        wb = excel.Workbooks.Open(filename)
    except com_error as e:
        if e.excepinfo[5] == -2146827284:
            print(f'Failed to open spreadsheet.  Invalid filename or location: {filename}')
        else:
            raise e
        sys.exit(1)

    # set worksheet
    ws1 = wb.Sheets('data')
    
    # Setup and call pivot_table
    ws2_name = 'pivot_table'
    wb.Sheets.Add().Name = ws2_name
    ws2 = wb.Sheets(ws2_name)
    
    pt_name = 'example'
    pt_rows = ['expense']
    pt_cols = ['products']
    pt_filters = ['date']
    # [0]: field name [1]: pivot table column name [3]: calulation method [4]: number format
    pt_fields = [['price', 'price: mean', win32c.xlAverage, '$#,##0.00'],  
                 ['price', 'price: sum', win32c.xlSum, '$#,##0.00'],
                 ['price', 'price: count', win32c.xlCount, '0']]
    
    pivot_table(wb, ws1, ws2, ws2_name, pt_name, pt_rows, pt_cols, pt_filters, pt_fields)
    
#     wb.Close(True)
#     excel.Quit()

Resources

• Jupyter Notebook: How to Create a Pivot Table in Excel with the Python win32com Module
• Automate Excel with Python
  • Examples with Pivot Table
• Using Python win32com to get list of Excel worksheets
• Excel VBA reference
• Workbook object (Excel)
• Worksheet object (Excel)